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M 20 17 GSM BSS Integration for Field Maintenance ET H IO TE LE C O STUDENT BOOK LZT1380709 R2A LZT1380709 R2A
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GSM BSS Integration for Field Maintenance
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STUDENT BOOK LZT1380709 R2A
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GSM BSS Integration for Field Maintenance
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DISCLAIMER
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This book is a training document and contains simplifications. Therefore, it must not be considered as a specification of the system.
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The contents of this document are subject to revision without notice due to ongoing progress in methodology, design and manufacturing.
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Ericsson shall have no liability for any error or damage of any kind resulting from the use of this document. This document is not intended to replace the technical documentation that was shipped with your system. Always refer to that technical documentation during operation and maintenance.
© Ericsson AB 2012
This document was produced by Ericsson.
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The book is to be used for training purposes only and it is strictly prohibited to copy, reproduce, disclose or distribute it in any manner without the express written consent from Ericsson.
This Student Book, LZT1380709, R2A supports course number LZU1088842.
© Ericsson AB 2012
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Table of Contents
Table of Contents
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1 CELL PLANNING PROCESS ..........................................................13 1
INTRODUCTION TO RAN INTEGRATION ..................................... 14
2
CELL PLANNING PROCESS .......................................................... 15 STEP 1: TRAFFIC AND COVERAGE ANALYSIS ........................ 15
2.2
STEP 2: NOMINAL CELL PLAN................................................... 16
2.3
STEP 3: SURVEYS (AND RADIO MEASUREMENTS)................ 17
2.4
STEP 4: SYSTEM DESIGN (FINAL CELL PLAN) ........................ 17
2.5
STEP 5: IMPLEMENTATION........................................................ 17
2.6
STEP 6: SYSTEM TUNING .......................................................... 17
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2.1
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THE IMPLEMENTATION PROCESS .............................................. 18
3.1
INSTALLATION ENGINEERING .................................................. 18
3.2
NETWORK ELEMENT TEST ....................................................... 19 BSC TEST PART....................................................................... 19
3.2.2
RBS TEST PART....................................................................... 21
3.2.3
INTEGRATION TEST ................................................................ 21
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3.2.1
3.2.4
CONDITIONS BEFORE STARTING ......................................... 22
3.2.5
CHECK OF DATA...................................................................... 23
3.2.6
BRINGING EQUIPMENT INTO SERVICE................................. 23
3.2.7
TEST CALLS ............................................................................. 23
3.2.8
TEST OF EXTERNAL ALARMS ................................................ 23
2 GSM RAN OVERVIEW ....................................................................25 1 1.1
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GSM SYSTEM ARCHITECTURE .................................................... 26 GENERAL..................................................................................... 26
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SWITCHING SYSTEM (SS) ......................................................... 26
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1.2
MOBILE SERVICES SWITCHING CENTER (MSC-S) .............. 26
1.2.2
GATEWAY MSC SERVER (GMSC-S) ...................................... 27
1.2.3
MOBILE MEDIA GATEWAY (M-MGW) ..................................... 27
1.2.4
HOME LOCATION REGISTER (HLR) ....................................... 27
1.2.5
VISITOR LOCATION REGISTER (VLR) ................................... 27
1.2.6
AUTHENTICATION CENTER (AUC)......................................... 27
1.2.7
EQUIPMENT IDENTITY REGISTER (EIR) ............................... 28
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1.2.1
GPRS SUPPORT NODE (GSN) ................................................... 28 SERVING GPRS SUPPORT NODE (SGSN) ............................ 28
1.3.2
GATEWAY GPRS SUPPORT NODE (GGSN) .......................... 28
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1.3.1
1.4
BASE STATION SUBSYSTEM (BSS) .......................................... 28
1.4.1
TRANSCODER CONTROLLER (TRC) ..................................... 28
1.4.2
BASE STATION CONTROLLER (BSC) .................................... 28
1.4.3
RADIO BASE STATION (RBS).................................................. 29
1.5 OPERATION AND SUPPORT SYSTEM RADIO AND CORE (OSS-RC)............................................................................................... 29
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RAN ARCHITECTURE .................................................................... 31
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2.2
TRANSCODER CONTROLLER (TRC) ........................................ 34 TRANSCODER AND RATE ADAPTOR (TRA).......................... 35 BASE STATION CONTROLLER (BSC) ....................................... 41
2.2.1
TRANSCEIVER HANDLER (TRH) ............................................ 41
2.2.2
TRC/BSC NODE........................................................................ 43
2.2.3
GROUP SWITCH (GS) .............................................................. 43
2.2.4
SUBRATE SWITCH (SRS) ........................................................ 44
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SIGNALING TERMINAL NO. 7 (ST7) ........................................ 45
2.2.6
PROCESSORS (RP AND CP)................................................... 45 RADIO BASE STATION (RBS)..................................................... 46
2.3.1
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2.3
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2.2.5
BTS VS. RBS............................................................................. 47
2.4 VAMOS-VOICE OVER ADAPTIVE MULTI-USERS ON ONE SLOT...................................................................................................... 47
3
RBS 6000 FAMILY........................................................................ 48
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2.5
ENHANCED GPRS – EGPRS ......................................................... 49 EDGE EVOLUTION ...................................................................... 51
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3 GSM RAN INTERFACES.................................................................53 1
INTRODUCTION ............................................................................. 54
2
A INTERFACE ................................................................................. 55
2.1
A-TER INTERFACE ...................................................................... 56
2.2
A-BIS INTERFACE ....................................................................... 58 A-BIS CONFIGURATION AND PROTOCOLS .......................... 59
2.2.2
LAPD UNCONCENTRATED ..................................................... 60
2.2.3
LAPD CONCENTRATED........................................................... 61
2.2.4
LAPD MULTIPLEXING .............................................................. 61
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2.3
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PCM LINK DEVICE TYPES............................................................. 63
3.1
EXCHANGE TERMINAL CIRCUIT (ETC) .................................... 63
3.1.1
ETC DIFFERENCES ................................................................. 63
3.1.2
RALTS AND RBLTS .................................................................. 64
3.1.3
RTLTTS AND RTLTBS .............................................................. 65
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REVIEW OF PCM LINK INTERFACES ........................................ 62
ABIS OPTIMIZATION ...................................................................... 66
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BANDWIDTH OPTIMIZATION................................................... 67
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4.1.1
A-INTERFACE OVER IP ................................................................. 69
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ABIS OVER IP ................................................................................. 71
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ABIS LOCAL CONNECTIVITY (ALC) .............................................. 74
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AIR INTERFACE.............................................................................. 78
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FREQUENCY BANDS .................................................................. 79
8.2
AIR INTERFACE CHANNELS ...................................................... 80
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8.1
TRAFFIC CHANNELS (TCHS) .................................................. 81
8.2.2
ADAPTIVE MULTI RATE (AMR) ............................................... 83
8.2.3
ADAPTIVE MULTI RATE WIDEBAND (AMR-WB) .................... 83
8.2.4
CONTROL CHANNELS (CCHS) ............................................... 86
8.2.5
BROADCAST CHANNELS (BCHS)........................................... 86
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8.3
BASE STATION IDENTITY CODE (BSIC) ................................... 88 CONTROL CHANNEL MULTIFRAME ....................................... 89
8.3.2
COMMON CONTROL CHANNELS (CCCHS) ........................... 90
8.3.3
MULTIPLE CCCH ...................................................................... 91
8.3.4
IMSI/TMSI .................................................................................. 92
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8.3.1
8.3.5
BCH AND CCCH CARRIERS .................................................... 96
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INTRODUCTION ........................................................................... 100
2
RBS 2000 ARCHITECTURE ......................................................... 101
2.1
REPLACEABLE UNITS (RU)...................................................... 101
2.2
DISTRIBUTION SWITCH UNIT (DXU) ....................................... 102
2.2.1
INSTALLATION DATABASE (IDB) .......................................... 103
2.2.2
OPERATION AND MAINTENANCE TERMINAL (OMT).......... 103
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RBS 2000 FAMILY......................................................................... 109
3.1
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THE UPDATED RBS 2106 V3.................................................... 109
BENEFITS ............................................................................... 109
3.1.2
IMPACTS ................................................................................. 110
THE UPDATED RBS 2206 V2....................................................... 111
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RBS 2X16 ...................................................................................... 112
5.1.1 6
BENEFITS ............................................................................... 111
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4.1.1
BENEFITS ............................................................................... 112
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3.1.1
RBS 2308....................................................................................... 113 BENEFITS ............................................................................... 113
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RBS 2111....................................................................................... 115
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RBS 2111 SECOND GENERATION ............................................. 118
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RBS 2409....................................................................................... 120
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ERICSSON RBS6000 PRODUCT FAMILY ................................. 121 RBS 6102.................................................................................. 122
10.2
RBS 6101.................................................................................. 123
10.3
RBS 6201.................................................................................. 123
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10.4
RBS 6601.................................................................................. 124
10.5
UNIT MIGRATIONS .................................................................. 124
11 11.1
MULTI-STANDARD RADIO ...................................................... 127
11.2
RBS 6000 TRANSPORT OPTIONS ......................................... 128
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REMOTE OMT OVER IP ............................................................. 129
5 COMMAND HANDLING ................................................................133 1
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DIGITAL UNIT FOR GSM ............................................................ 125
MML COMMAND HANDLING ....................................................... 134
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ANATOMY OF AN MML COMMAND ......................................... 134
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1.1
COMMAND STRING ............................................................... 134
1.1.2
RBS TECHNICIAN COMMANDS ............................................ 135
1.2
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1.1.1
USING ALEX TO RESEARCH COMMANDS ............................. 136
COMMAND DESCRIPTIONS (CODS) .................................... 136
1.2.2
PRINTOUT DESCRIPTIONS (PODS) ..................................... 137
1.2.3
OPERATIONAL INSTRUCTIONS (OPIS) ............................... 138 HELPFUL PRINT COMMANDS.................................................. 138
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1.2.1
6 CELL-RELATED CONCEPTS .......................................................139 INTRODUCTION ........................................................................... 140
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HARDWARE VIEW OF THE GSM NETWORK ............................. 142
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LAI AND CGI............................................................................... 143
CELL DEFINITION AND CONFIGURATION ................................. 146
3.1
MSC CELL DEFINITION............................................................. 146
3.2
BSC CELL DEFINITION AND CONFIGURATION...................... 146 INTERNAL AND EXTERNAL CELLS ...................................... 148
3.2.2
CELL DESCRIPTION DATA.................................................... 149
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3.2.3
CELL CONFIGURATION FREQUENCY DATA....................... 152
3.2.4
DISCONTINUOUS TRANSMISSION (DTX) ............................ 152
3.2.5
POWER DATA CONFIGURATION.......................................... 153
3.2.6 CELL SYSTEM INFORMATION DATA SENT ON SACCH AND BCCH .......................................................................................... 155 3.2.7
MEASUREMENT FREQUENCIES .......................................... 156
3.2.8
NEIGHBOR CELL DEFINITION .............................................. 158
3.2.9
MEASUREMENT REPORTS (MRS) ....................................... 159
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LOCATING............................................................................. 161
3.2.11
HYSTERESIS ........................................................................ 167
EDGE EVOLUTION ....................................................................... 171
4.1
EDGE PERFORMANCE TODAY AND TOMORROW................ 171
4.1.1
NETWORK PERFORMANCE OF TODAY .............................. 171
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MULTI-BAND CELL FEATURE .................................................. 169
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3.3
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3.2.10
4.1.2 ENHANCED APPLICATIONS PERFORMANCE OVER EDGE 171
EDGE EVOLUTION – DUAL CARRIER ..................................... 172
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EDGE EVOLUTION PERFORMANCE BOOST ...................... 172
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4.1.3
4.2.1
BENEFITS ............................................................................... 173
4.2.2
OPERATOR VALUE ................................................................ 173
4.2.3
BENEFITS FOR THE CONSUMER......................................... 174
4.2.4
TECHNICAL DESCRIPTION ................................................... 174
4.2.5
COMMANDS AND PRINTOUTS ............................................. 175
7 MANAGED OBJECTS ...................................................................177 MANAGED OBJECT (MO) CONCEPT .......................................... 178
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LOGICAL MODEL G12.................................................................. 179
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2.1.1
MCPA APPLICATION AND MCTR .......................................... 180
2.1.2
MO CLASSES FOR BTS LOGICAL MODEL G12 ................... 181
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MO FUNCTIONALITY.................................................................... 183
3.1
DXU-RELATED FUNCTIONALITY ............................................. 183
3.1.1
CENTRAL FUNCTION (CF) .................................................... 183
3.1.2
INTERFACE SWITCH (IS)....................................................... 183
3.1.3
TIMING FUNCTION (TF) ......................................................... 183
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CONCENTRATION (CON) ...................................................... 183
3.1.5
DIGITAL PATH (DP) ................................................................ 183 TRU-RELATED FUNCTIONALITY ............................................. 184
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3.2
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3.1.4
TRANSCEIVER CONTROLLER (TRXC)................................. 184
3.2.2
TRANSMITTER (TX) AND RECEIVER (RX) ........................... 184
3.2.3
TIMESLOTS (TS)..................................................................... 184
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3.2.1
DEFINING MANAGED OBJECTS ................................................. 185 ADDRESSING OF MANAGED OBJECTS ................................. 185
4.2
MO STATES ............................................................................... 188
4.3
FREQUENCY HOPPING ............................................................ 189
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4.3.1
SYNTHESIZER HOPPING ...................................................... 189
4.3.2
BASEBAND HOPPING ............................................................ 190
4.3.3
TERMINAL ENDPOINT IDENTIFIERS (TEIS)......................... 191
4.4
DIGITAL CONNECTION POINTS (DCPS) ................................. 195
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INTRODUCTION ........................................................................... 198
2
RBLT CONNECTIONS .................................................................. 199
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3.1
BRINGING SITE INTO SERVICE ............................................... 202
3.2
DEBLOCKING A SITE ................................................................ 203
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4
CELL CONNECTION AND ACTIVATION...................................... 204
4.1
CONNECT CELL TO BTS .......................................................... 204
4.2
ACTIVATE CELL ........................................................................ 204
4.3
TRANSITIONING FROM HALTED TO ACTIVE ......................... 205
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VERIFICATION........................................................................... 205
4.5
CELL RESOURCE DATA ........................................................... 205
4.6
BTS CONFIGURATION DATA ................................................... 206
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LOADING NEW RBS SOFTWARE................................................ 207
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4.4
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Cell Planning Process
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Objectives
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1 Cell Planning Process
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Determine where the RAN Integration process – as part of the entire Cell Planning Process – comes in and the general steps to be taken for integration: › Discuss the Cell Planning Process › Determine the Network Implementation Process › Apply the RAN Integration Test
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Figure 1-1: Objectives
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Introduction to RAN Integration
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The Global System for Mobile Communication (GSM) Radio Access Network (RAN) Integration process1 is an important part of the complete network realization. This chapter gives an introduction to where the RAN Integration process – as part of the entire Cell Planning Process – comes in. Furthermore, it describes the general steps to be taken for integration.
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The remaining chapters are intended for Radio Base Station (RBS) field technicians in order to provide them with knowledge of the BSC-related parts of the integration process. For network operation staff, this course provides knowledge about the various integration procedures related to the RBS site.
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Increased familiarity with the RAN Integration process, that is how RAN-related systems are initially set up, defined, configured, etc., will aid in all operation and maintenance procedures vital to both the Base Station Controller (BSC) and RBS systems, and to how they work together.
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Note that this process was formerly known as “BSS Site Integration”.
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Cell Planning Process
Cell Planning Process
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Cell planning can briefly be described as all the activities involved in determining which sites should be used for the radio equipment, which equipment should be used, and how the equipment should be configured.
System Growth
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Traf Datafic
T Covraffic Qu erage alit y
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To ensure coverage and to avoid interference, each cellular network needs planning. The major activities involved in the cell planning process are represented in Figure 1-2.
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Step 1: Traffic & Coverage Analysis
Step 6: System Tuning
Step 5: Implementation
ign es e ell ddata g C ra ve f. Co on ec Sit
Initial Planning
lan ll P Ce
es Sit n Pla FQ
Step 2: Nominal Cell Plan
Step 3: Surveys
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Step 4: System Design
Figure 1-2: The Cell Planning Process
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Step 1: Traffic and Coverage Analysis
The cell planning process is started by a traffic and coverage analysis. The analysis should produce information about the geographical area and the expected capacity need. The different types of data collected are:
Cost
Capacity
Coverage
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Grade of Service (GoS)
Available frequencies
Speech Quality Index
System growth capability
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Population distribution
Car-usage distribution
Income-level distribution
Land-usage data
Telephone-usage statistics
Other factors, such as subscription charges, call charges, and costs of mobile stations
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The traffic demand (meaning, how many subscribers access the system and how much traffic is generated) provides the basis of cellular network engineering. The geographical distribution of the traffic demand can be calculated using demographic data, such as:
Step 2: Nominal Cell Plan
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Upon compilation of the data received from the traffic and coverage analysis, a nominal cell plan is produced. The nominal cell plan is a graphical representation of the network and it simply looks like a cell pattern on a map. However, there is a lot of work behind it (as previously described).
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Nominal cell plans are the first cell plans produced, and these form the basis of further planning. Quite often, a nominal cell plan, together with one or two examples of coverage predictions, is included in tenders. Coverage and interference predictions are usually initiated at this stage. Such planning needs computer-aided analysis tools for radio propagation studies, for example, Ericsson’s planning tool, known as the TEMS Cell Planner (TCPU).
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2.3
Step 3: Surveys (and Radio Measurements)
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Cell Planning Process
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The nominal cell plan has been produced, and the coverage and interference predictions have been roughly verified. Now, it is time to visit the sites where the radio equipment is to be placed and to perform radio measurements. The former is important because it is necessary to assess the real environment to determine whether it is a suitable site location for a cellular network. The latter is even more important because better predictions can be obtained using field measurements of the signal strengths in the actual terrain where the mobile station is to be located.
Step 4: System Design (Final Cell Plan)
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2.5
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After optimization and when the predictions generated by the planning tool can be considered reliable, a dimensioning of the RBS equipment, BSC, and MSC is performed. The final cell plan is produced. As the name implies, this plan is later used at system installation. In addition, a document called Cell Design Data (CDD) containing all cell parameters for each cell is completed.
Step 5: Implementation
System installation, commissioning and testing are performed following the final cell planning and system design. This step is described in further detail later on in this chapter.
2.6
Step 6: System Tuning
Once the system has been installed, it is continually evaluated to determine how well it meets the demands. This is called system tuning and involves:
A check that the final cell plan has been implemented successfully
An evaluation of customer complaints
A check that the network performance is acceptable
Changing parameters and undertaking other measures (if needed)
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The system needs constant re-tuning, due to the fact that the traffic and number of subscribers continuously increase. Eventually, the system reaches a point where it must be expanded so that it can manage the increasing load and new traffic. At this point, a coverage analysis is performed and the cell planning process cycle starts all over again.
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The Implementation Process
3.1
Installation Engineering
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• Project Specification • Proposed Network Design
Radio Site Installation and Integration
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Radio Site Investigation (Site Survey) Survey Report
Site Install. Doc.
Radio Site Design Documents (“As Built Documentation”)
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Radio Site Installation Documents
Radio Site Investigation Report
Customer
Figure 1-3: Installation Engineering
Figure 1-3 illustrates the main steps of the implementation of a new radio site. The output from the System Design step (Step 4) in the Cell Planning Process results in a hardware order (for example, BSC or RBS) directed to the factory.
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Installation engineering personnel perform site investigations, which involve taking a closer look at the actual location where the site is to be built. This results in installation documentation, which is put into a binder for each site. The installation documentation contains all information needed to build the site, for example, floor plans, cable drawings, antenna arrangement drawings, grounding plans, site material lists, etc. The material needed to build the site is then ordered according to the installation documentation.
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When all equipment has arrived at the proposed site, the installation can begin. After installing the equipment, it is time to check its functionality. First, the nodes are tested for full functionality on their own; this is called an Installation Test.
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Cell Planning Process
Next, the interworking function is tested; this is called the Integration Test. The two tests together make up the Network Element Test, which is further explained below.
Network Element Test
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After installation and testing, all site installation documentation is put into a binder – called the “As Built Documentation”, which, in the Ericsson world, is called the C-module.
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Figure 1-4 shows the main process steps of the Network Element Test of the BSC and RBS. Network Element Test
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RFI (Ready For Integration)
Factory Test
Test Instructions
RFT (Ready For Traffic)
Installation Test
Integration Test
Test Instructions
Test Instructions
Installation Test Report
Integration Test Report
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Factory Test Report
Figure 1-4: Network Element Test
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BSC Test Part The Network Element Test of the BSC is described in a section of the AXE (product name for Ericsson’s switch) library called the H-module. The main steps are described in this section.
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3.2.1.1
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Factory Test
3.2.1.2
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The purpose of this test phase is to test all hardware. The Input Output Group (IOG) or Adjunct Processor Group (APG) is configured with the exchange data, and the hardware-dependent exchange data is loaded.
Installation Test
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The purpose of this test phase is to start up the AXE at the customer site and to perform all site-dependent tests, such as tests of the alarm panel, external alarms, and cabling to the Distribution Frame (DF). In addition, a final test is performed.
3.2.1.3
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After this test phase, the network element is in the Ready For Integration (RFI) state.
Integration Test
The purpose of this test phase is to load all network-dependent exchange data and to integrate the network element into the network. Traffic tests are performed to verify the interworking function of the network element. The integration tests performed for the BSC are:
MSC-RAN integration test
OSS integration test
TRI integration test (if RBS 200 is connected)
RBS integration test (RBS 200 or RBS 2000)
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After this test phase, the network element is in the Ready For Traffic (RFT) state and can be taken into service.
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A more thorough explanation of the steps of the Integration Test part is given later on in this chapter.
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RBS Test Part
3.2.2.1
Factory Test
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3.2.2
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Cell Planning Process
Site Installation Test
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3.2.2.2
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The cabinets are tested before they leave the factory. This test is called Cabinet Assembly Test. The test verifies that the cabinet hardware is working and that it has the right configuration. In addition, radio measurements are performed on the radio parts and protocols, which are delivered with the cabinet.
3.2.2.3
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Once the cabinet has been installed, the Site Installation Test (SIT) is performed to verify the function of the RBS hardware after shipping. Parameters that are site specific, for example, external alarms, cable attenuation and alarm limits are set during the test.
Integration Test
This test is done in close cooperation with the BSC personnel. The test is performed to verify that the RBS and BSC are interworking properly. The RBS is brought into service via the BSC, and test calls are made to see that the cell is capable of receiving traffic. A more detailed explanation will be given in the next section.
3.2.3
Integration Test
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This test is also referred to as the Network Integration Test in the Site Installation Test manual (EN/LZT 123 2683). This is the manual that is used by the Field Maintenance personnel. The Integration Test of RBS 2000 Series (detailed in document 18/1538-APT 210 09 Uen B in the H-Module), for example, contains identical information, and this is what is used by the Operations personnel.
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Figure 1-5 shows the Integration Test procedure. The steps are further explained later in this section.
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Preconditions At the BSC: • The cell has been defined • Managed Objects (MOs) have been defined • A-bis path has been defined
• Data checking
• Bringing equipment into service
At the cell site: • All site installation tests have been performed
Ready For Traffic (RFT)
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• Testing calls
Externally:
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Figure 1-5: RBS Integration Test
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• Testing external alarms
• All transmission links are working • All transport modules have been loaded with correct data
3.2.4
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Integration Test
Conditions before Starting
Before the tests can be performed the following conditions must be fulfilled:
Network Element (NE) tests of the BSC must have been performed
An integration test of the Mobile Switching Center (MSC) / Visitor Location Register (VLR) must have been performed; for example, it must be possible to make calls
Prerequisites and test preparations in the Site Installation Test manual should be fulfilled
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Exchange data for the definition of Managed Objects (MOs), cells, and A-bis paths must be loaded
Transmission to the Base Transceiver Station (BTS) site must function satisfactorily
If Transport Modules (TMs) are used, they must be loaded with the correct data
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3.2.5
Check of Data
17
Cell Planning Process
The following checks should be performed before the site is taken into service:
Check that the PCM supervision is correctly defined
Check that all cell data is correctly defined
Check that the right BTS software is loaded in the IOG or APG
Check that the A-bis path is correctly defined
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Check that the Transceiver Group (TG) data is correct
Bringing Equipment Into Service
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3.2.6
To bring the RBS into service, perform the following:
Bring the MOs into service
Deblock the MOs
Activate the cell(s)
Check that the RBS is correctly configured
NOTE: All these steps will be discussed in more detail in Chapter 8.
Test Calls
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3.2.7
3.2.8
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When the RBS has been brought into service, the commissioning staff make test calls to verify that the RBS is fully functional. The test calls are made separately on receiver paths A and B. This is done to verify that the two antenna paths function properly. During the test calls, the BSC personnel check all BSC functions.
Test of External Alarms This test is performed to verify that the correct external alarm string shows up in the BSC when the alarm is triggered by the RBS commissioning staff.
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GSM RAN Overview
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Objectives
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2 GSM RAN Overview
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Discriminate the GSM RAN system and unit interworking identifying the individual components in the RAN system, both in the BSC and RBS, using student material and instructor explanation:
› List the GSM Switching System components › List GSM Radio Access Network (RAN) components › Identify the two parts of the Operation Support System – Radio and Core (OSS RC) › Explain the BSC and TRC functional units
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Figure 2-1: Objectives
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GSM System Architecture
1.1
General
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1
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GSM BSS Integration for Field Maintenance
AuC
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HLR
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Ericsson’s GSM System is a mobile telephone system containing the frequency bands GSM 800, GSM 900, GSM 1800 and GSM 1900. The GSM network is divided into three major systems: Core Network (CN), Base Station Subsystem (BSS), and the Operation and Support System Radio and Core (OSS -RC).
EIR
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MSC-S
RBS
TDM/IP
RBS
BSC/TRC PCU
TDM/IP
MGW
ATM/TDM /IP
PSTN ISDN PLMN
MGW
RBS
SGSN
IP Backbone
Internet
GGSN
Intranet
OSS -RC
Figure 2-2: GSM Basic Network
Switching System (SS)
IO
1.2
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Mobile Services Switching Center (MSC-S) The MSC-S is responsible for setting up, routing, and supervising calls to and from the mobile subscriber (mobility management, handover, ect). Short messages, routed from the SMS-GMSC or sent from the Mobile Station (MS) / User Equipment (UE), are relayed in the MSC. The MSC-S is implemented using the Ericsson AXE and APG processor.
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17
GSM RAN Overview
Gateway MSC Server (GMSC-S)
Mobile Media Gateway (M-MGW)
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The GMSC Server is an MSC serving as an interface between the mobile network and other networks, such as the Public Switched Telephony Network (PSTN), Integrated Services Digital Network (ISDN) and other Public Land Mobile Networks (PLMN) for mobile terminating calls. It contains an interrogation function for retrieving location information from the subscriber’s HLR. The GMSC contains functions for rerouting a call to the Mobile Subscriber according to the location information provided by the HLR.
1.2.4
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The M-MGW connects the Mobile Core Network with external networks such as WCDMA and GSM Base Station Subsystem, PSTN Networks or other Mobile Network. The M-MGw works in conjunction with the MSC Server (Softswitch).
Home Location Register (HLR)
The Home Location Register (HLR) is a database used for storage and management of mobile subscriptions. The HLR is considered the most important database since it stores permanent data on subscribers – including subscribers’ service profiles, location information, and activity status. When individuals buy a subscription from an operator, they are registered in the HLR of that operator. The HLR can be implemented with the MSC/VLR or as a stand-alone node.
Visitor Location Register (VLR)
The Visitor Location Register (VLR) is a database containing temporary subscribers’ information needed by the MSC to service visiting subscribers. The VLR is always integrated with the MSC. When a mobile station (MS) roams into a new MSC area, the VLR connected to that MSC will request data about the MS from the HLR. Later, if the MS makes a call, the VLR will have the information needed for call set-up without having to interrogate the HLR each time.
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1.2.5
1.2.6
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Authentication Center (AUC) A unit called the Authentication Center (AUC) provides authentication and encryption parameters that verify the mobile subscriber’s identity and ensure the confidentiality of each call. The AUC protects network operators from different types of fraud found in today’s cellular world.
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GSM BSS Integration for Field Maintenance
Equipment Identity Register (EIR)
17
1.2.7
20
The Equipment Identity Register (EIR) is a database containing information about the mobile equipment identities. This register prevents calls from stolen, unauthorized, or defective MSs. The AUC and EIR are implemented as standalone nodes or as a combined AUC/EIR node.
GPRS Support Node (GSN)
1.3.1
Serving GPRS Support Node (SGSN)
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1.3
1.3.2
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The SGSN is a primary component in the GSM network using GPRS and is a new component in GSM. The SGSN forwards incoming and outgoing IP packets addressed to/from an MS that is attached within the SGSN service area.
Gateway GPRS Support Node (GGSN)
Like the SGSN, the Gateway GPRS Support Node (GGSN) is a primary component in the GSM network using GPRS and is a new component. The GGSN provides the interface to the external IP packet networks.
1.4 1.4.1
Base Station Subsystem (BSS)
Transcoder Controller (TRC)
IO
The Transcoder Controller (TRC) provides the RAN with rate adaptation capabilities. A device that performs rate adaptation is called a transcoder. The bit rates per channel are decreased using transcoders. This saves on transmission links between the MSC and the BSCs.
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Base Station Controller (BSC) The Base Station Controller (BSC) manages all the radio-related functions of a GSM network. It is essentially a high-capacity switch that provides functions such as MS handover, radio channel assignment, and the collection of cell configuration data. A number of BSCs may be controlled by each MSC.
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1.4.3
Radio Base Station (RBS)
20
The Radio Base Station (RBS) handles the radio interface to the MS.
17
GSM RAN Overview
One RBS can serve one, two, or three cells. A group of RBSs is controlled by one BSC. Ericsson has two base station families; they are RBS 200 and RBS 2000.
Operation and Support System Radio and Core (OSS-RC)
M
1.5
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Ericsson’s Operation and Support System (OSS-RC) provides a way of supporting the centralized, regional, and local operations and maintenance activities required by a cellular network. OSS is the functional entity from which the network operator monitors and controls the system.
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OSS can be viewed as a two-level management function. The centralized control of a network through the installation of a Network Management Center (NMC), with subordinate Operation and Maintenance Centers (OMCs), is advantageous (Figure 2-3). NMC staff can concentrate on system-wide issues, whereas local personnel at each OMC can concentrate on short-term, regional issues. The OMC and NMC functionality can be combined in the same physical installation or implemented at different locations.
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The OSS is designed to provide a coherent management system that supports a number of network elements. Examples of these network elements are MSC, BSC, RBS, VLR, HLR, EIR, AUC, and MIN.
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OSS-RC NMC
OMC
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OMC MIN HLR
BSC
BTS
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AUC / EIR
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GSM BSS Integration for Field Maintenance
NMC - Network Management Center
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OMC - Operation and Maintenance Center
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Figure 2-3: Operation and Support System (OSS-RC)
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2
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GSM RAN Overview
RAN Architecture
20
All radio-related functions are concentrated in the RAN ( BSS ). The RAN is responsible for establishing and maintaining connections between MSs. The RAN allocates radio channels for voice and data messages, makes the radio connections, and serves as a relay station between MSs and the MSC (Figure 24).
Transcoder Controller (TRC) – The TRC performs rate adaptation of speech information. The function can either be implemented in a separate hardware node or together with the BSC in a TRC/BSC node. In the TRC, the bit rate per channel is decreased from 64 kbps to 16 kbps.
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The RAN consists of two or three nodes depending on how the functions are implemented, they are:
Base Station Controller (BSC) – The BSC controls all the radio-related functions for the system. The BSC equipment, like the MSC, is an AXE application.
Radio Base Station (RBS) – The RBS is the radio equipment needed to serve one or more cells in the GSM network. The RBS 200 and the RBS 2000 are Ericsson implementations of the GSM specification for a Base Transceiver Station (BTS), which is the equipment that serves one cell.
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17
GSM BSS Integration for Field Maintenance
MSC
StandAlone TRC
20
TRC
TRA HW
TRA HW
BSC
StandAlone BSC
No TRA HW
No TRA HW
RBS
RBS
RBS
RBS
RBS
RBS
RBS
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RBS
O
RBS
M
No TRA HW
BSC
Figure 2-4: GSM RAN Architecture
The three different BSC and TRC configuration types are as follows:
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Stand-alone TRC The stand-alone TRC node allows a flexible location of the transcoder resources. Typically, the TRC is located at or near the MSC, but it is controlled by the BSC regardless of location. 16 BSCs can be connected to one TRC. Stand-alone BSC The BSC is optimized for low- and medium-capacity RAN systems and is a complement to the TRC/BSC, especially in rural and suburban areas. A stand-alone BSC can handle up to 4,095 transceivers (TRXs), by using the feature “Beyond 2048 TRXs per BSC” (same as 4K TRX) with APZ 212 55, APG 43, GARP-2. Combined TRC/BSC The TRC/BSC is suitable for medium and high capacity BSC applications, that is, urban and suburban area networks. This node can handle up to 4,095 transceivers (TRXs) as described before. 15 stand-alone BSCs can be connected to the TRC/BSC (Figure 2-5).
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GSM RAN Overview
17
Up to four (4) MSCs
20
MSC MSC MSC MSC
BSC
BSC
BSC
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BSC
M
TRC/BSC
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Up to 15 Remote BSCs
16th BSC can be isolated from TRC (in case of a Stand–alone TRC)
Figure 2-5: TRC/BSC Capacity
The same TRC/BSC can be connected to up four MSCs at the same time. Nowadays there is also a feature called MSC in Pool where the TRC can be connected to several MSCs in order to improve the network traffic. MSC Service Area 2
MSC Service Area 1
BSC 1C
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BSC 2C
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PSTN
BSC 2B BSC 1B
BSC 2A
TRC/BSC 1A TRC 2A MSC/VLR 1 MSC/VLR 2
AUC GMSC
HLR EIR
MSC Boundary BSC Boundary PCM Links Base Station (RBS) Figure 2-6: Hardware View of a Network (1 of 2)
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Network
Network
MSC
MSC
TRC
BSC
BSC
OR
MSC
BTS BTS BTS BTS BTS BTS
BTS BTS BTS
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MSC
BSC
BTS BTS BTS
BSC
M
BSC
TRC/BSC
BTS BTS BTS
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TRC/BSC
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GSM BSS Integration for Field Maintenance
BSC
BTS BTS BTS BTS BTS BTS BTS BTS BTS
2.1
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Figure 2-7: Hardware View of a Network (2 of 2)
Transcoder Controller (TRC)
The Transcoder Controller (TRC) node contains the pooled transcoder resources and can be a stand-alone node or combined with the BSC. It is connected to the MSC via the A interface, and to the BSC via the A-ter interface. The TRC node has the ability to support up to 16 BSCs over the A-ter interface. The transcoders in the various Transcoder and Rate Adaptor (TRA) pools in a TRC can be shared between all BSCs, associated with the TRC. One of the connected BSCs may be residing on the same physical platform as the TRC, that is, in a combined TRC/BSC network element.
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One TRC can be connected to up to four MSCs (refer to Figure 2-8). This makes it possible to build rather large TRCs supporting several MSCs. One BSC is still controlled by one specific MSC.
- 34 -
The TRC can contain several transcoder resource pools, one pool per type of transcoder resource, for example, Full Rate (FR), Enhanced Full Rate (EFR), Half Rate (HR), Adaptive Multi Rate FR (AMR FR), and Adaptive Multi Rate HR (AMR HR).
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ETC ETC
ETC
Group Switch
TRAU ? SRS
ST7
If a TRAU is present, the node is a TRC.
RPD
RP
CP
RP
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SP
RP
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RP
BSC
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MSC/ VLR
ETC
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GSM RAN Overview
Figure 2-8: TRC Hardware Configuration
TE LE C
The A interface signaling remains unchanged in the new system structure. For the communication between the TRC and a remote BSC, a C7/SS7-based Ericsson proprietary communication protocol is used. In the case of a combined TRC/BSC, internal signaling between the TRC and BSC part is used. The TRC node handles the A-ter transmission interface resources. The operation and maintenance signaling and the handling of the A-ter interface are similar to the current implementation on the A interface.
IO
At call set-up and after signaling connection set-up, an assignment request is sent via the MSC to the BSC. The request is sent directly to the BSC and can pass transparently through the TRC. The BSC receives the assignment request and requests a transcoder device from the TRC, also indicating the A interface Circuit Identification (CIC) to be used for this specific call. The TRC allocates a transcoder device and the timeslot on the A-ter interface, which is connected to the A interface CIC, specified by the MSC. The TRC replies to the BSC, which establishes the connection to the mobile.
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LZT1380709 R2A
Transcoder and Rate Adaptor (TRA) The TRA is the function responsible for the speech coding and rate adaptation of incoming speech and data from the MSC and the RBS. The hardware where the function is implemented is called Transcoder and Rate Adaptation Board (TRAB). It has the following basic functions:
Transcoding of speech information - Speech at 64 kbps to/from the MSC is transcoded to 13 kbps to/from the RBS, enabling four compressed channels to be multiplexed onto one 64 kbps channel, that is, if FR or EFR is used. These have a bit
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GSM BSS Integration for Field Maintenance
17
rate of 13 or 15.1 kbps. For HR, speech is transcoded to 6.5 kbps
Additional control information – 3 kbps for FR, 0.9 for EFR, and 1.5 kbps for HR are added to the transcoded rate to the RBS, giving a final output of 16 kbps or 8 kbps. The control information, which is called in-band signaling, basically indicates what type of information the information contains, for example, speech or data.
Rate adaptation of data information - The maximum data rate supported at present in GSM is 14.4 kbps per TS. With High Speed Circuit Switched Data (HSCSD) it is possible to have higher bit rates, since then the MS will be assigned more than one TS.
Discontinuous Transmission (DTX) – DTX functions on both uplink and downlink. This reduces the interference in the network and saves mobile batteries.
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The following figure illustrates how the TRA works:
64 kbps
0
23 (T1) or 31 (E1)
ABCD 23 (T1) or 31 (E1)
0
A B C D
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GS
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16 kbps
ABCD 64 kbps NC NC
0
A B C D 31
TRAB
Figure 2-9: TRA Functionality
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GSM RAN Overview
17
The incoming 64 kbps is sent through the Group Switch (GS) to the TRA. Four 64 kbps channels are transcoded to 16 kbps (FR and EFR) and multiplexed onto one 64 kbps. They are then sent out via the GS to the RBS on the A-bis interface.
2.1.1.1
Multiplexing and Demultiplexing of Channels
20
NOTE: The various interfaces between the RAN nodes (A interface, A-ter, A-bis, etc.) will be further discussed in Chapter 3. Additionally, hardware features in the TRC, such as the Group Switch (GS), will be discussed later in this chapter.
M
The transcoder multiplexes a number of transcoded channels into one 64 kbps channel, used between the BSC and BTS. The number of multiplexed channels depends on the type of speech codec:
Four traffic channels for FR or EFR
Eight traffic channels for HR
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In terms of hardware, a TRAB consists of 32 devices, requires 32 GS inlets, and can handle 24 Traffic Channels (TCHs). In an FR or EFR TRAB:
Six multiplexers (MUXs) handle 24 multiplexed channels to the BTS
24 demultiplexers (DEMUXs) handle the demultiplexed channels to the MSC
Four DEMUXs are statically connected to each MUX device
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In an HR TRA-EM:
LZT1380709 R2A
Three MUXs handle 24 multiplexed channels to the BTS
24 DEMUXs handle the demultiplexed channels to the MSC
Eight DEMUXs are statically connected to each MUX device
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MUX
DEMUX DEMUX
MUX
DEMUX
MUX
DEMUX
DEMUX
MUX
DEMUX
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MUX
MUX
DEMUX
DEMUX
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MUX
DEMUX
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MUX
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GSM BSS Integration for Field Maintenance
TRAB
TRAB
Figure 2-10: TRAB Configured for FR/EFR and HR
In both configurations, two TRABs are used.
The new version of TRA hardware, TRA R6B, has 192 channels per board.
2.1.1.2
Semi-permanently Connected vs. Pooled Transcoders
IO
Before the transcoder equipment can be seized for a connection to the BTS, it must be physically and logically connected, and manually deblocked. The transcoder equipment requested can be either semi-permanently connected or pooled transcoders:
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Semi-permanently connected through the GS for FR only. Once the connection is established, it is possible to use it for traffic as soon as synchronization is established between the transcoder and the BTS.
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GSM RAN Overview
TRU
Timeslot 0 Timeslot 1
Transcoder 9 Transcoder 10 Transcoder 11 Transcoder 12
Timeslot 2 Timeslot 3 Timeslot 4 Timeslot 5
20
17
BSC Transcoder 7 Transcoder 8
Transcoder 13 Transcoder 14
Timeslot 6 Timeslot 7
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With a semi-permanent connection, every timeslot requires a dedicated transcoder in the BSC. Although this would ensure that there were always transcoders available, it is unnecessary and expensive. Figure 2-11: Semi permanent Connection of Transcoders to Timeslots
Pooled transcoder devices are seized according to TRA capability and availability. The connections through the GS, for a transcoder device seized from a transcoder pool, are set up on a per-call basis.
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BSC
TRU
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FR Pool
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Transcoder 7
Timeslot 0
Transcoder 8
Timeslot 1
Transcoder 9
Timeslot 2 Timeslot 3
EFR Pool
Timeslot 4
Transcoder 7
Timeslot 5
Transcoder 8
Timeslot 6
Transcoder 9
Timeslot 7
With pooled transcoders: A transcoder is seized from the pool when the call starts… … and is released when the call ends.
Figure 2-12: Pooled Transcoder Concept
If it is semi-permanently connected, the transcoder device is always connected to the same timeslot (TS) in the RBS. This means that the resource is not accessible to others, even if there is no ongoing traffic. One TRA device is required for each air TS, which will require a lot of TRA boards. To put the transcoders in a pool, transcoders are seized on a percall basis leading to better utilization of the installed transcoder hardware.
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GSM BSS Integration for Field Maintenance
0
23/31
AB
B
“TRADEV”-3
A
23/31
0
GS
20
“TRADEV”-4
17
Figure 2-13 further illustrates the pooled transcoder concept, including the TRC hardware involved:
To RBS 1
To RBS 2
To MSC
A
M
B
O
SRS SRS
AB
2 3 4
31
AB
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0 1
NC NC
“TRADEV”-2&&-31
TRA
Figure 2-13: TRA Devices in a “Pool”
In this configuration of the transcoder, the TRA resources can be set to be in
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pools. In one TRC/BSC there can be different pools, for example, one pool with EFR devices, one with FR devices, and one with HR devices. Depending on the MS equipment that should be connected, the TRC/BSC seizes a device that is dependent on each mobile station's capabilities, e.g., not all MSs can handle EFR, and releases the device when the call is terminated. This results in less hardware being required, since all mobile subscribers in the BSC area will not call simultaneously. There is seldom congestion due to no available TRA devices in the pool.
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To be able to handle semi-permanently connected transcoders, there is no need for extra hardware. However, if pooled transcoders are to be used, the TRC/BSC must have a Subrate Switch (SRS) as seen in Figure 2-14. The reason for this is that different TRA resources, e.g., FR and EFR, are integrated onto the same 64 kbps, and the GS (as previously mentioned) cannot switch lower than 64kbps. The SRS can switch down to 8 kbps and can then put different 16 kbps devices on the same 64 kbps. SRS functionality is further detailed in a later section.
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GSM RAN Overview
Base Station Controller (BSC)
17
2.2
20
The stand-alone BSC has been developed and optimized especially for rural and suburban areas and is a complement to the TRC/BSC node in the BSC product portfolio.
O
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The BSC’s most important task is to ensure the highest possible utilization of the radio resources. The main functions of the BSC are radio network management, RBS management, TRC handling, transmission network management, internal BSC O&M, and handling of MS connections. The BSC contains a Transceiver Handler (TRH), consisting of both hardware and software. It is located on a Regional Processor (RP) for the Group Switch – the Regional Processor Group (RPG). Thus, one RPG serves several transceivers. There can be several RPGs in the BSC as well.
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The BSC does not contain any transcoders. It utilizes transcoder resources from a central TRC/BSC, or from a stand-alone TRC node. The BSC is connected to the TRC/BSC, or to the TRC via the A-ter interface. ETC
TRC
ETC
ETC ETC
Group Switch
BTS
TRH
SRS
RPG
ST7
IO
RP
RPD
RP
SP
RP
RP
If a TRH is present, the node is a BSC.
CP
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Figure 2-14: BSC Hardware Configuration
2.2.1
LZT1380709 R2A
Transceiver Handler (TRH) The TRH performs the activities that are required to control the RBS and the transceivers, and is responsible for several functions including:
Handling of signaling on the Link Access Protocol on the Dchannel (LAPD) link between BSC-BTS
Handling of the logical channel addressing part of signaling to/from the BTS and MS
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GSM BSS Integration for Field Maintenance
Processing of measurement data from the BTS and MSs
Operation and maintenance of the BTS
17
20
Figure 2-15 illustrates the principle of the TRH. 0
23/31
S
M
To BTS
The TRH Device is called
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RHDEV
S
0
SNT: RHSNT-0
TRH
31
Example: SNT= RHSNT-0 DEV= RHDEV-1&&-24
Figure 2-15: TRH Functionality
2.2.1.1
TRH Devices and Switching Network Terminals (SNTs)
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Each SNT in Figure 2-16 has 32 devices. The SNT is called “RHSNT” and it handles the TRH devices, named “RHDEV”. The hardware connected to the GS is referred to as “device” hardware. A device is the resource that each SNT has connected to the GS. Depending on the device hardware and software loaded, the device can have different capabilities.
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Each transceiver in the RBS must have a signaling connection to the BSC. The device handling the signaling connection to the RBS is the RHDEV. One RHDEV is semi- permanently connected to one transceiver in the RBS. As previously mentioned, the RHSNT has 32 devices, but in reality only 24 of them are usable (RPG2). This is due to the fact that one TS is used for test purposes and the others are excluded so as not to load the TRH with tasks. The TRH explained above is the latest TRH that uses RPG hardware. The older hardware that uses Regional Processor Device (RPD) hardware has only eight RHDEVs per board, seven of which can be used.
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2.2.2
17
The LAPD protocol is explained further in Chapter 3.
TRC/BSC Node
20
The TRC/BSC node comprises all hardware that constitutes the stand-alone TRC and BSC nodes. ETC ETC
ETC
BTS
M
MSC/ VLR
ETC
Group Switch
O
TRAU
SRS
ST7
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TRH
RP
RPD
RP
SP
RPG
RP
RP
If both a TRAU and a TRH are present, the node is a TRC/BSC.
CP
Figure 2-16: TRC/BSC Hardware Configuration
2.2.3
Group Switch (GS)
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The GS is the central part of the TRC/BSC. The GS connects an incoming channel with an outgoing channel. For example, it can connect any incoming PCM timeslot and send it out on any outgoing PCM link on any timeslot. The GS comprises Time Switch Modules (TSMs) and Space Switch Modules (SPMs) and can switch down to 64 kbps. If switching needs to be done to lower bit rates, for example, 16 kbps, the SRS must be used.
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TRC/BSC
RBS
GS
ETC
ETC
DXU
RBLT
20
RALT
TRU
TRAU TRH
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Subrate Switch (SRS)
O
Figure 2-17: Call Path in TRC/BSC
M
SRS
2.2.4
17
From MSC
BTS
Subrate switching allows for the connection of rates lower than 64 kbps. The rates allowed are n*8 kbps (where n=1 to 7). An example of how the SRS can be used to switch calls to different destinations using only one TRA resource is illustrated in Figure 2-18. TRAU
16 kbps 16 kbps
16 kbps
16 kbps
ty ali s on cti kbp n 4 u A f ts 6 s TR nver 6 kbp co to 1
TRH
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64 kbps
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GS
64 kbps
ETC
MSC
ETC
BTS1
ETC
BTS2
4 x 64 kbps
Figure 2-18: SRS in the TRC/BSC
Four 64 kbps timeslots that contain speech arrive at the BSC from the MSC. The TRH controls the call set-up and determines whether the SRS should be used, which TRA should be used, the call type, destination BTS etc.
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17
The GS sets up connections to the TRA which transcodes the four 64 kbps channels into four 16 kbps. The 4x16 kbps channels are then multiplexed into one 64 kbps channel, which is returned to the GS.
20
In this example, the destination of two of the calls is BTS1, and of the other two calls is BTS2. The TRH has this information and determines that it is necessary to set up a connection towards the SRS.
M
The SRS switches the 16 kbps subrate channels to two 64 kbps channels that are returned to the GS. Hereafter, the GS can set up connections towards BTS1 and BTS2, which contain the correct subrate channels.
Signaling Terminal No. 7 (ST7)
TE LE C
2.2.5
O
The SRS is required when pooled transcoders are used. In addition, it is needed when utilizing LAPD multiplexing, which occurs when the speech and signaling to the RBS is multiplexed onto the same 64 kbps. This will be explained further in Chapter 3.
The MSC must have the ability to signal with the BSC. This is done using Signaling Terminals (STs). The signaling devices are called, for example, C7ST2C for E1 PCM links. The signaling between the MSC and BSC is slightly different in a T1 network, since T1 has a separate signaling network. This means that there is no connection between the GS and the ST. Generally, there are two signaling TSs between the BSC and MSC. Whereas one is sufficient for all signaling, the second is installed for redundancy purposes.
2.2.6
Processors (RP and CP)
ET H
IO
The Regional Processors (RPs) are designed to execute simple high-repetition functions and are mainly used for the direct control of the hardware units of the application systems. These hardware units offer the traffic devices of the exchange, for example, TRA.
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The RPD device hardware can supply TRH or C7 signaling and is integrated with the RP. The RPG has the same functionality as the RPD, but it has higher capacity than the RPD. In the BSC, the RPG – with different software loaded – can serve as a TRH, C7, or ST7.
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Radio Base Station (RBS)
M
20
The Radio Base Station (RBS) includes all radio and transmission interface equipment needed on the radio site. Ericsson employs two versions of the RBS – the RBS 2000 and the RBS 200. Each RBS operates at a given pair of frequencies. One frequency is used to transmit signals to mobile stations, and the other one to receive signals from mobile stations.
External alarms
TE LE C
OMT Interface
O
Test
A-bis Interface
BSC or
BSC/ TRC
Figure 2-19: RBS 2000 Hardware Configuration
ET H
IO
NOTE: Each RBS hardware unit – DXU, TRU, CDU, etc. – will be described in Chapter 4. Also, Figure 2-20 shows the “classic” configuration for the RBS 2000 series. However, the high-capacity RBS 2000s differ somewhat. These differences will be described in Chapter 4.
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BTS vs. RBS
20
As mentioned earlier, the GSM specification for the radio equipment necessary to serve one cell is called a BTS. RBS 200 and 2000 series are Ericsson-specific BTS product lines.
Base Transceiver Station (BTS)
M
• Generic acronym used by all GSM vendors and operators
Radio Base Station (RBS)
O
• Defined in the GSM specification as “Equipment required to support one cell”
TE LE C
• Ericsson product line of BTSs
• Can support several cells (e.g., 3-sector site) • For example, an RBS 2106 can be considered a BTS even though one “box” can actually be three BTSs
Figure 2-20: Distinction Between BTS and RBS
2.4
VAMOS-Voice over Adaptive Multi-users on One Slot
ET H
IO
› Full Rate-1 call per TS
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› Half Rate-2 calls per TS
› VAMOS-4 calls per TS with no voice quality degradation Figure 2-21: VAMOS- Voice over Adaptive Multi-user channels on One Slot
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GSM BSS Integration for Field Maintenance
–
Up to 32 half rate speech channels on each RU
–
Each burst sent from a RBS can with VAMOS contain speech up to two different mobiles instead of only one in classic GSM.
–
VAMOS can work with mobiles supporting SAIC (Single Antenna Interference Cancellation), but new mobiles supporting VAMOS 1 and 2 increases the performance.
–
VAMOS is supported by all EDGE enabled RU’s for almost all base stations with some exceptions.
O
M
20
17
Vamos is feature that doubles the circuit switched call capacity by increasing more speech channels in each timeslot of the same RU.
RBS 6000 Family
IO
TE LE C
2.5
–
ET H
Figure 2-22: RBS 6000 family
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The RBS 6000 base station family is designed to meet the increasingly complex challenges facing operators today. RBS 6000 is built with tomorrow's technology and at the same provide backwards-compatibility with the highly successful RBS 2000 and RBS 3000 product lines. RBS 6000 base stations offer a seamless, integrated and environmentally friendly solution and a safe, smart and sound roadmap for whatever tomorrow holds. All RBS 6000 base stations support multiple radio technologies.
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3
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GSM RAN Overview
Enhanced GPRS – EGPRS
M
20
EGPRS is an extension of GPRS, but at higher data rates. EDGE is required to be introduced in existing systems with given infrastructure. Since the 8PSK modulation is more susceptible to noise and interference than GMSK, there is a need to adapt the transmission scheme used to the interference situation. This link quality control (LQC), a key feature of the EDGE concept, is essential for providing to each user the maximum throughput that the rapidly changing conditions allow at the moment. The LQC is the main reason why the EDGE RLC protocol is somewhat different from the corresponding GPRS protocol. A-bis A-bis
BSC/ BSC/ BSC/ BSC/ PCU PCU PCU PCU
A
MSC/VLR MSC/VLR
O
BTS BTS BTS BTS
SGSN SGSN SGSN SGSN
Gn
BGW BGW
SOG SOG
Gr (MAP)
Gs
TE LE C
Gb
HLR HLR Gi (IP)
GGSN GGSN
IP Network
Gn
Backbone IP Network
New hardware, software and dimensioning New software and dimensioning New dimensioning New software
Figure 2-23: The EGPRS System Architecture
ET H
IO
The modulation type that is used in GSM is the Gaussian minimum shift keying (GMSK), which is a kind of phase modulation. This can be visualized in a I/Q diagram that shows the real (I) and imaginary (Q) components of the transmitted signal. Transmitting a zero bit or one bit is then represented by changing the phase by increments of + _ p. Every symbol that is transmitted represents one bit, i.e., each shift in the phase represents one bit.
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17
GPRS = General Packet Radio System
M
EGPRS = GPRS + EDGE modulation
EDGE = Enhanced Data rates for Global Evolution
O
Figure 2-24: The Abbreviation
TE LE C
The chosen modulation method, 8PSK is a linear modulation, where three consecutive bits are mapped onto one symbol in the I/Q-plain. Since number of symbols sent within a certain time is kept the same as for GMSK, but each symbol now represents three bits instead of one, the total data rate is increased with a factor three.
GMSK Modulation GMSK
EDGE: 8PSK Modulation
Q
(0,1,0)
(0,0,0)
“1”
(0,1,1)
I
I
ET H
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(0,0,1)
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“0”
Q
(1,1,1)
(1,0,1)
(1,1,0) (1,0,0)
“1 bit per symbol”
“3 bits per symbol”
Figure 2-25: EDGE Modulation
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GSM RAN Overview
Edge Evolution › 16 QAM
TE LE C
O
M
20
› 32 QAM
bitsPer per symbol” “4“4Bits Symbol”
bits Per per symbol” “5“5Bits Symbol”
Figure 2-26: Evolved EDGE-16/32 QAM
Edge Evolution is a further step to enhance the total throughput speeds. Incase of 8 PSK which sends 3 bits per symbol, increases speed three times on the radio link depending on the C/I ratio. 16 QAM is a further enhancement by allowing to send 4 bits per symbol enhancing the speed further.
ET H
IO
32 QAM further is capable of sending 5 bits per symbol, which is the maximum supported modulation technique currently.
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IO
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O
Intentionally Blank
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GSM RAN Interfaces
O
Objectives
M
20
3 GSM RAN Interfaces
TE LE C
Recognize the various interfaces and protocols for those interfaces, studying the GSM topology and differentiating each other: › Identify and Explain the A, Ater and Abis interfaces › Understand the Abis optimization concept › Indetify the caracteristics of Abis over IP configuration › Understand the concept of Abis local connectivity › Explain the characteristics of the Air Interface › List the various Air Interface channels
ET H
IO
Figure 3-1: Objectives
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1
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Introduction
20
The purpose of this chapter is to describe the various interfaces – and protocols for those interfaces – between the GSM nodes described in Chapter 2. NOTE: Many of the overhead slides in the instructor’s presentation will not appear in this book.
A interface
A-ter interface
Abis interface
TE LE C
O
M
There are four primary interfaces within the RAN where traffic and signaling information is received and transmitted. These interfaces are:
Air interface
The A interface exchanges information between the MSC/VLR and M-MGW ( CORE ) and the TRC. The A-ter interface exchanges information between the TRC and BSCs. The Abis interface transmits information between the BSC and BTS, and the Air interface operates between the BTS and MS.
Air
IO
Interface
Abis Interface
RBS
A-ter Interface
BSC
TRC
A Interface
M-MGW
ET H
MS
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Figure 3-2: GSM RAN Interfaces
There are basically two ways of building the interfaces:
2 Mbps PCM (E1) interface - The E1 physical channel is divided into 32 timeslots, each with a bit rate of 64 kbps.
1.5 Mbps PCM (T1) interface - The T1 physical channel is divided into 24 timeslots, each with a bit rate of 64 kbps.
PCM Link Interfaces
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GSM RAN Interfaces
A Interface
17
2
20
The A interface provides two distinct types of information, signaling and traffic, between the MSC and the RAN. Speech is transcoded in the TRC, and the SS7 signaling is transparently connected through the TRC or on a separate link to the BSC. Figure 3-3 shows the mapping of the traffic information on the Pulse Code Modulation (PCM) link:
T1
TE LE C
O
M
E1
ET H
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Figure 3-3: A Interface (E1 and T1)
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A-ter Interface
TE LE C
O
M
20
The A-ter interface is the link between the TRC and the BSC. In the TRC, speech is transcoded from 64 kbps to 16 kbps. That means 13 kbps of speech information and 3 kbps of in-band signaling information. Figure 3-4 and Figure 3-5 show how the traffic information is mapped to the PCM links:
ET H
IO
Figure 3-4: A-ter Interface (E1)
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17
GSM RAN Interfaces
ET H
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Figure 3-5: A-ter Interface (T1)
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A-bis Interface
20
The A-bis interface is responsible for transmitting traffic and signaling information between the BSC and the BTS. The transmission protocol used for sending signaling information on the A-bis interface is Link Access Protocol on the D Channel (LAPD).
M
RBS 2000 and RBS 6000 are administrated and controlled remotely from BSC. All handling of RBS equipment, including configuration, maintenance, and administration, is controlled by BSC. RBS software loading and administration are also governed by the BSC.
TE LE C
O
Concentration/Multiplexing/Multi Drop functionality is a part of DXU (Distribution Switch Unit) in RBS 2000 and DUG (Digital Unit GSM) in RBS 6000. They are modeled as separate Managed Object (MO) within BSC (MO CON). There is a priority value given to users of Abis paths. Signalling has higher priority than speech/data. Within signalling, there will be two priority levels, the CF link has highest priority (1) and TRXC signalling has lower priority (2). Priorities are used in recovery, higher priority links are recovered first and they will steal lower priority links if no other links are available.
ET H
IO
G12 is the name of the BTSs Logical Model supported by RBS 2000 and RBS 6000.
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Figure 3-6: Abis Interface Between BSC and RBS 2000
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GSM RAN Interfaces
A-bis Configuration and Protocols
LAPD Unconcentrated
LAPD Concentrated
LAPD Multiplexing
TE LE C
O
M
20
Signaling over the A-bis interface between the BSC and the RBS 2000 is quite complex. There is signaling to both the Distribution Switch Unit (DXU) and the Transceivers Units (TRU). Speech is coded by the TRAU in the TRC or TRC/BSC. Signaling information is handled inside the BSC by the TRH. The physical layout of the traffic and signaling to each TRU on the A-bis interface depends on the format chosen to facilitate the transfer of information. There are three possible protocol formats that can be designated for information transfer on the A-bis interface:
ET H
IO
REMEMBER: The E1 networks use TS 0 on the A-bis interface to provide a synchronization reference to the RBS. In T1 networks, frame sync information is extracted from the T1 link to synchronize the RBS with the network. In these systems, an internal synchronization source is fitted into the DXU, which gives stable and reliable synchronization.
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GSM BSS Integration for Field Maintenance
LAPD Unconcentrated
Sync for E1, and Traffic or Signaling for T1
64 kbps
1
TRX Signaling
64 kbps
2
64 kbps
3
64 kbps
4
M
0
Traffic (4x)
64 kbps
5
one TRX
Traffic (4x)
64 kbps
6
T1
64 kbps
7
16 kbps 16 kbps 16 kbps
Traffic (4x)
one TRX
Traffic (4x)
Timeslot 5
0 1 2 3 Timeslot 6
16 kbps
23 / 31
E1
16 kbps
TRX Signaling
TE LE C
. . . . .
64 kbps
O
0 1 2 3 4 5 6 7 8 9 10
20
With LAPD unconcentrated, signaling for each TRU is sent on a dedicated 64 kbps channel and is accompanied by two 64 kbps channels, each carrying four 16 kbps sub-multiplexed voice/data channels.
16 kbps 16 kbps 16 kbps
4 5 6 7
ET H
IO
Figure 3-7: A-bis Interface (E1) with LAPD Unconcentrated
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17
GSM RAN Interfaces
LAPD Concentrated
20
LAPD concentrated is recommended for all cells, but in particular those with three or more TRUs. (NOTE: For cells with one or two TRUs per cell, LAPD multiplexing provides the most efficient A-bis transmission). With LAPD concentration, each TRU needs 2.25 PCM timeslots. Hence, it is possible to fit up to 13 TRUs on one 2 Mbps PCM line (E1), as compared to 10 TRUs without this feature.
64 kbps 64 kbps 64 kbps 64 kbps
. . . . .
Sync for E1, and Traffic or Signaling for T1 4xTRX Signaling (TRXs 0-3) 4xTraffic
64 kbps 64 kbps 64 kbps 64 kbps
23 / 31
E1
T1
64 kbps 64 kbps 64 kbps
TRX 0
4xTraffic 4xTraffic
4xTraffic
16 kbps 16 kbps 16 kbps
TRX 2
16 kbps
Timeslot 6
0 1 2 3 Timeslot 7
4xTraffic 4xTraffic
16 kbps
TRX 1
4xTraffic
TE LE C
64 kbps
0 1 2 3 4 5 6 7 8 9 10 11 12
M
64 kbps
O
0 1 2 3 4 5 6 7 8 9 10 11 12
16 kbps
TRX 3
16 kbps 16 kbps
4xTraffic
4 5 6 7
4xTRX Signaling (TRXs 4-7) 4xTraffic
TRX 4
4xTraffic
Figure 3-8: A-bis Interface (E1) with LAPD Concentrated
LAPD Multiplexing
ET H
IO
2.2.4
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As mentioned, LAPD multiplexing is recommended for small cells, i.e., those with one to two TRUs. With LAPD multiplexing, each TRU needs two PCM timeslots. Hence, it is possible to fit up to 15 TRUs on one 2 Mbps PCM line (E1), as compared to 10 TRUs without LAPD multiplexing. With two TRUs in a cell, normally only 14 of the available channels on the air interface are used for traffic and the remaining two air timeslots for Broadcast Control Channel (BCCH) and Stand-alone Dedicated Control Channel (SDCCH) signaling. Therefore, transmission is needed for approximately 14 x 16 kbps, i.e., 3.5 PCM timeslots. The remaining half-timeslots are used for LAPD signaling for the two TRUs. In total, four PCM timeslots are used for two TRUs.
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64 kbps
64 kbps
64 kbps
. . . . .
0
Sync for E1 and Traffic/Signaling for T1
1
2xTRX Signaling / 2xTraffic
2
4xTraffic
16 kbps
3
4xTraffic
16 kbps
TRX 0
Timeslot 1
16 kbps
TRX 0 Signaling
16 kbps
TRX 1 Signaling
16 kbps
2 3
Air TS number
20
0 1 2 3 4 5 6 7 8 9 10
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Timeslot 2
64 kbps
4
64 kbps
TRX 1 4xTraffic
4 5 6 7
16 kbps 16 kbps
M
16 kbps 23 / 31
E1
O
T1
2.3
TE LE C
Figure 3-9: A-bis Interface (E1) with LAPD Multiplexing
Review of PCM LINK Interfaces
In figure below, fill in the blanks with the appropriate name of the PCM link interface. Try not to look at the previous pages for the answers.
MSC
MSC
?
?
A Interface
A Interface
TRC
TRC/BSC
A-ter Interface
ET H
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?
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A-bis Interface
BSC
?
?
A-ter Interface
Remote BSC A-bis Interface
?
A-bis Interface
?
BTS
BTS
Network Schematic with Stand-Alone TRC
BTS Network Schematic with combined TRC/BSC
Figure 3-10: GSM RAN Interfaces Review
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PCM Link Device Types
3.1
Exchange Terminal Circuit (ETC)
20
3
17
GSM RAN Interfaces
O
M
The ETC board is the common hardware in the AXE to handle the PCM transmission links, in this case, between the MSC and BSC, and between the BSC and RBS (BTS). The links can either be 1.5 Mbps (T1) or 2 Mbps (E1) PCM links. The two link types use different hardware, that is, for BYB 501, which is the latest building practice, the 1.5 Mbps uses ETC-T1 boards and the 2 Mbps uses ETC5 boards. What differs, though, between the ETC boards towards the MSC and those towards the RBSs, is that they have different software loaded. This means that the resources are named differently. TRC/BSC
RBS
TE LE C
MSC
ETCs
ETCs
ETC
MALT ?
RALT ?
RBLT ?
MALT ?
RALT ?
MALT ?
RALT ?
A Interface
RBS
A-bis Interface
ETC
RTLTT ?
A-ter Interface
RBS ETC BSC ETC
RTLTB ?
RBLT ? A-bis Interface
MALT = MSC A-Interface Line Terminal
RALT = RTS (Radio Transmission and Transport Subsystem) A-Interface Line Terminal
RTLTT = RTS A-Ter Line Terminal TRC
RTLTB = RTS A-Ter Line Terminal BSC RBLT = RTS A-Bis Line Terminal
IO
Figure 3-11: GSM RAN PCM Link Device Types
ET H
3.1.1
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ETC Differences ETCs in the MSC, TRC, and BSC (or TRC/BSC) use the same type of hardware, since they are all based on the same type of platform (AXE), but they are loaded with different types of software. This means that they have slightly different functions as well. The Digital Path (DIP) is the name of the function used for supervision of the connected PCM lines. ITU-T has issued recommendations that state how the PCM links should be supervised. All these recommendations are implemented in the DIP function and in the ETC.
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Depending on whether the PCM link goes from or to the MSC (along the A interface), or to the RBS (along the A-bis interface), the ETC will have different names:
20
RALTs and RBLTs
TE LE C
3.1.2
M
MALT – MSC A interface Line Terminal (MALT) is the name of the ETC in the MSC that goes to the TRC or TRC/BSC. RALT – Radio Transmission and Transport Subsystem (RTS) A interface Line Terminal (RALT) is the name of the ETC in the TRC or TRC/BSC that goes to the MSC. This is also known as “ETRALT”. RBLT – RTS A-Bis interface Line Terminal (RBLT) is the name of the ETC in the BSC or TRC/BSC that goes to the RBSs. This is also known as “ETRBLT”.
O
Each timeslot/device, which is 64 kbps, on the PCM link to the MSC is called a “RALT” device. The device is a resource that the BSC can store information on. In this case, it is either signaling or speech towards the MSC. Timeslots/devices on the PCM link to the RBS are called RBLT devices. In the case of the RBLT, stored BSC information is either LAPD signaling or speech/data towards the RBS. The number of RBLT devices is 32 on an E1 PCM link and 24 on a T1 PCM link.
IO
It should also be noted that for E1 transmission, the RBLT devices 0, 32, 64, and 96 are not used. 0 on the PCM link is used for synchronization and, therefore, cannot be used for other purposes. This is not the case in a T1 PCM link, where synchronization is performed differently. In the T1 system, the devices are also called RBLT24 devices.
ET H
The numbering principle is the same for both RALT and RBLT devices.
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Figure 3-12 shows the different names and concepts associated with the PCM links in E1 and T1 systems.
© Ericsson AB 2012
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A Interface
A-bis Interface Device
DIP
Device
Timeslot
SNT SNT
Timeslot
RBLT-1&&-31 RALT-1&&-31
31 (E1)
RALT-0&&-23
ETC 23 (T1)
RALT0 0
ETRBLT-0 ETRALT-0
ETC
DIP
RBLT0
RBLT-0&&-23
20
0
17
GSM RAN Interfaces
RBLT-33&&-63
ETRBLT-1
RALT-33&&-63 RALT1 RALT-24&&-47
ETC
ETC
ETRALT-1
RBLT1
RBLT-24&&-47
RBLT-65&&-95
ETC
M
ETRBLT-2
SNTP (e.g. TSM-10-1)
RBLT2
RBLT-48&&-71
RBLT-97&&-127
ETC
O
ETRBLT-3
SNTP (e.g. TSM-9-3)
TE LE C
GS
RBLT3
RBLT-72&&-95
Figure 3-12: ETC-Related Concepts
3.1.3
RTLTTs and RTLTBs
Like MALTs, RALTs, and RBLTs, ETCs have special names along the A-ter interface as well:
ET H
IO
RTLTT – RTS A-Ter Line Terminal TRC (RTLTT) is the name of the ETC in the stand-alone TRC (or TRC/BSC) that goes to a standalone BSC. RTLTB – RTS A-Ter Line Terminal BSC (RTLTB) is the name of the ETC in the stand-alone BSC that goes to the stand-alone TRC (or TRC/BSC).
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Abis Optimization
20
Abis Optimization, which is Ericsson’s solution for delivering Packet Abis over TDM transport networks, saves bandwidth by transferring only bits that contain data. All other bits (for example, those that were previously used to maintain a constant bit rate to fit the PDH channel format) are no longer inserted.
M
Ericsson has integrated the Abis Optimization solution into its base station subsystem (BSS).
O
Abis Optimization is a feature to achieve bandwidth savings on the Abis interface. Bandwidth savings are achieved by removal of redundant information and packing of frames in both uplink and downlink.
TE LE C
Bandwidth savings are also accomplished by introducing the super channel concept. A super channel is one E1 or one T1 link, or a fraction of one E1 or one T1, where 64 Kbit/s consecutive Abis timeslots can be used as a wideband connection for sending signaling and payload as LAPD frames between BSC and BTS. As all traffic and signaling share the same wideband connection, statistical multiplexing gains are achieved. The number of E1/T1 links required per site with Abis Optimization depends on site configurations and traffic mix. In the T1 markets, one RBS 2106/2206 with up to 12 TRXs can cover three sectors with only one T1. With “classic” Abis, two T1s would be required for this configuration.
IO
BSC
E1/T1
GS
ETC
DXUDXU-21
TRH
ET H
TRA
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PGW
TRX TRX
GPH
Figure 3-13: A-bis Optimization Architecture
In many locations, operators have also limited EGPRS to one timeslot, giving subscribers a peak performance of at most 59.2 kbps. However, by deploying Packet Abis, operators can quadruple the speed at most times of the day without adding transmission capacity, thereby giving users the ability to, say, surf the internet at more than 230 kbps.
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17
› Abis Optimization delivers Packet Abis over TDM transport networks, saving bandwidth by solely transferring bits that contain informative data
20
› It is based on a software upgrade of the RBS, and the introduction of a packet gateway (PGW) in the BSC, to terminate the Packet Abis protocol
O
M
› To save even more bandwidth, one may add a Site Integration Unit (SIU) at RBS sites deploy the feature Abis over IP
TE LE C
Figure 3-14: Abis Optimization Concept
To save even more bandwidth, one may add a Site Integration Unit (SIU) at RBS sites to exploit statistical multiplexing gains between RBSs. Using SIU, it is possible to implement the feature Abis over IP.
4.1.1
Bandwidth Optimization
In E1 markets, one E1 can support two RBSs with up to 18 TRXs. For standard base station configurations, this could translate into a saving of up to 50%.
› Packet Gateway is needed in the BSC – Handles LAPD packeds
› Introduce the Super Channel concept
IO
– Wide band connection for sending signalling and payload
› DTX needs to be activated
ET H
– Mechanism that allows the radio transmitter to be switched off
› No static allocation of transmission for GPRS/EGPRS is needed – Use avaiable transmission on the Super Channel
› Redundant information is removed from AMR/GPRS/EGPRS frames – Eg.: MCS-1 frames will take much less Abis resources compared on MCS9 Figure 3-15: A-bis Optimization Bandwidth Optimization
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Figure 3-16: Abis Over Satellite
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GSM RAN Interfaces
A-Interface over IP
20
A-interface over IP enables transmission bandwidth savings and improved speech quality in MS-MS calls. As transcoders can be placed in CN, compressed speech can be transmitted over the A-interface instead of sending speech with 64-kbps Pulse-Code Modulation (PCM) over a TDM link. The feature also enables Transcoder Free Operation (TrFO) when codec types used in both ends of a call are compatible and no transcoders are involved in the call.
O
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The A-interface over IP feature adds IP transmission capability for A interface user plane in BSS. This feature supports transport of both compressed and uncompressed speech. Over the A interface the speech is transported in UDP/RTP packets.
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A-interface over IP supports two architectural scenarios at the same time in the BSS. In the first scenario the transcoder resources in the Core Network (CN) are used and speech is transmitted in compressed form over IP between BSS and CN. In the second scenario the transcoder resources in BSS are used and the speech is transmitted as PCM over IP between BSS and CN.
› The A-interface over IP feature adds IP transmission capability for A interface user plane in BSS › This feature supports uncompressed speech
transport
of
both
compressed
and
IO
› A-interface over IP supports two architectural scenarios at the same time in the BSS. In the first scenario the transcoder resources in the Core Network (CN) are used and speech is transmitted in compressed form over IP between BSS and CN
ET H
› In the second scenario the transcoder resources in BSS are used and the speech is transmitted as PCM over IP between BSS and CN
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Figure 3-17: A-Interface Over IP
With TDM transmission over the A interface each call needs one 64kbps TS in each direction. With A-interface over IP one FR call (FR, EFR, AMR-FR) will require 13 kbps for the payload and approximately 16 kbps for RTP/UDP/IP headers, that is approximately 29 kbps in each direction. With DTX this figure will be further reduced.
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MSC-S
A/IP
Mc
MSC-S
20
17
A-interface over IP uses IP based transport of A-interface user plane data. A BSS supporting A-interface over IP connects to a CN through a Mobile Services Switching Center-Server (MSC-S) and a Media Gateway (MGW) in a layered architecture.
A/IP
BSS
BSS
MGW
A/IP
PCM Compressed
MGW
= Signalling = User plane
A/IP
TRAU
PCM Compressed
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IP based protocol stack
Nb
O
TRAU
Mc/IP
M
Mc/IP
IP based protocol stack
= Possible location for a transcoder
Figure 3-18: A-interface over IP General View
A-interface over IP is an optional feature that configures the BSC/TRC for IP transport of A-interface substituting traditional TDM transport. The feature requires specific Regional Processor (RP) hardware; the A-Interface Gateway (AGW). The BSC/TRC supports up to 63 AGW RPs. One AGW RP handles upto 900 simultaneous calls.
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A-interface over IP is supported on new installations of BSC/TRC nodes based on AXE810 hardware.
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A-interface over IP user plane transports either PCM coded speech or compressed speech over IP. Circuit switched data and fax services can also be transported with A-interface over IP. Transcoding in BSC/TRC requires a Transcoder and Rate Adaptation Unit (TRAU). The operator configures the BSC/TRC per codec type; with regard to which codec types that have transcoder support in BSC/TRC, and which codec types that do not. Transcoders in BSC/TRC, when available, are only used for calls that need transcoding. This feature together with the features SIGTRAN support in BSC/TRC, Gb over IP and Abis over IP makes it possible to set up an all-IP BSS, where all payload and all signalling go over IP.
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GSM RAN Interfaces
Abis over IP
17
6
20
The Abis over IP solution enables operators to use IP and Ethernet transport networks to connect RBSs to the BSC and thereby benefit from the lower costs of IP- and Ethernet-based transport services. The solution also opens the door to shared transport with WCDMA and LTE to integrated transport solutions for RBS sites. The main equipment used to implement this solution is the Site Integration Unit (SIU).
The SIU adds transport sharing functionality, new GSM features and Site-LAN and Site Aggregation functionality to an Ericsson RBS site. For an Ericsson GSM network it adds Abis over IP, Abis Local Connectivity and improved Abis Optimization for the RBS 2000 family (except RBS 2409) and the RBS 6000 family.
›
For a combined GSM and WCDMA site it adds transport sharing functionality over both Ethernet and E1/T1 backhaul. Transport sharing makes the introduction of a WCDMA or LTE network in an Ericsson GSM environment more economical.
›
The SIU has an Ericsson unique synchronization solution that works over virtually any backhaul technology, including Satellite backhaul, without the need for a GPS solution at the RBS site.
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Figure 3-19: Site Integration Unit (SIU)
IO
The SIU is the common transmission module in a Multi Standard RBS6000. It also provides Ethernet interfaces for RBS2000 providing native Abis over IP for GSM.
ET H
Bandwidth is dynamically shared between all radio technologies on a site, optimizing peak capacity for HSPA and LTE services.
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The SIU supports backhauling of multi standard RBSs (including 2G/3G/LTE) over both Ethernet and E1/T1 transmission services with advanced QoS and shaping functionality minimizing the requirements on the transport network. Legacy RBSs can also be supported via the Circuit Emulation Service. Full Ericsson RAN integration through OSS-RC Management System guarantees smooth operations management. The SIU is 1U high and 19 inch wide unit which has been designed to be native fit and can be directly mounted into 2000, 3000 or 6000 series RBSs without exceeding available power and air budget. Alternatively it can be mounted in any available 19 inch standard rack. It requires +24 or -48 Volts standard RBS voltage minimizing the need for extra power supply.
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SIU
Native IP co-transport RBS 2000 / 3000
Multivendor co-transport RBS 2000 / 3000 / other
SIU
SIU
SIU
M
Circuit Emulation
2G/3G/LTE co-transport RBS 6000
20
Native IP for GSM RBS 2000
17
The figure bellow shows the various possibilities/scenarios where the SIU could be applied.
SIU
O
L2/L3 Transport
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IP over E1/T1
TDM Transport
BSC
RAN Switch/Router
RNC
SIU
Figure 3-20: SIU Application Overview
The SIU is fully integrated into the RBS 6000 with an increased forwarding capacity of 6 Gb/s for future proof site aggregation architectures, including hubbing and cascading and/or anticipated traffic growth.
ET H
IO
Another hardware that can be integrated into the RBS 6000 is the Transport Connectivity Unit. It also does the same function of the SIU and is installed inside the cabinet 6000. It supports 6 TG’s and also is possible to configure for using IP over E1/T1.
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GSM RAN Interfaces
Figure 3-21: Transport Connectivity Unit (TCU-02)
›
Integrated part of Ericsson solution
›
Native IP modules
›
Power integrated
›
OSS integrated
›
GSM / WCDMA / LTE transport sharing
›
IP RAN over TDM or L2/L3 transport
Cell site
3G
LTE
IO
GSM
IP over TDM or L2 or L3
– Including CES and IP SEC
›
Transport Nw
Multi-vendor solution
ET H
– Leveraging Ericsson + other
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Multi RAN
IP over any transport
Figure 3-22: Ericsson RBS Cabinet with Built-In Transport
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GSM BSS Integration for Field Maintenance
Abis Local Connectivity (ALC)
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Abis Local Connectivity (ALC) is an optional feature requiring the STN node that makes it possible for operators to reduce Abis bandwidth requirement to sites where there is at least a fair amount of local traffic. The basic idea is not to transport the speech any further than necessary. All signaling will still go to the BSC and the MSC, but if both legs of a call are served by the same STN node the speech will not be sent to the BSC to be switched in the core network. Switching the speech in the STN node instead of in the core network saves Abis bandwidth and increases the speech quality as the speech path delay goes down. This effect is very noticeable when using Abis Local Connectivity in combination with Abis over satellite.
TE LE C
Abis Local Connectivity provides the possibility to switch speech calls locally in the STN node. Local switching can be done if both legs of a call are handled by the same STN node and they use the same speech codec. When a call is locally switched there are no speech frames sent on Abis Upper although signaling, including measurement reports, are sent to and from the BSC as normal. Abis Local Connectivity is supported on the SIU and the RBS 2409 hardware. The BSC and the MSC are largely unaware that the call is locally switched, and a speech path from the BSC, via the MSC and back to the BSC is set up as normal. Abis Local Connectivity will not save any resources in the network except bandwidth on Abis and CPU capacity in the STN node and the PGW. A locally switched call will get a better speech quality than a normal call due to shorter speech path delay and due to that the call is not transcoded twice. The latter is the same increase in speech quality that is achieved with TFO.
ET H
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A call can only be locally switched if the two call legs use the same speech codec. It shall be noted that local switching of AMR calls require that the Tandem Free Operation (TFO) is activated. In order to maximize the probability for a call to be locally switched two different codec matching methods can be used.
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The first method controlled by the BSC is based upon choosing one of EFR, FR or HR codec to be the preferred one in Abis Local Connectivity cells. If the preferred codec can't be allocated for any reason the call will be set up using another codec as long as there are any available resources in the cell. The more advanced speech codecs with varying codec rates, AMR-FR, AMR-HR and AMR-WB may occasionally be used in Abis Local Connectivity cells to serve mobiles without support for the preferred codec.
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The second method is based upon activating the codec matching function within the STN node. This method aligns the bearer capability of the Calling and Called party towards to a common list of codecs that are supported by both parties. This common list of codecs is also aligned towards a preferred configured list of codecs in the STN node. The two codec matching methods shall not be used simultaneously.
M
The fact that local switching needs the same speech codec for both legs of a call means that the dynamic mode adaptation features DYMA, DHA and Abis Triggered Half Rate Allocation may interfere with the operation of local switching by changing the codec for one of the call legs.
O
Identification of which speech channels that together form the two legs of a call can only be made at call setup. Three different tagging methods can be chosen from for the purpose of call leg matching.
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In order to continue local switching after handover the STN node tries to match the handover target channel description with the existing channels handled by the STN node. For STN to be able to correctly identify the handover target channel it is important that all radio channel descriptions are unique both within the STN node and within all neighbor cells. All non-speech traffic and all speech traffic that is not locally switched is sent to the BSC as normal without being impacted by Abis Local Connectivity. Abis Local Connectivity is mainly implemented in the STN node, but needs some support both from the BSC and from the circuit switched core network. There is no impact on the BTS or on the packet core network.
ET H
IO
STN monitors the signaling to all served RBSs and mobiles and makes a small addition to the call setup signaling to be able to identify which two call legs that forms a call. Both legs of the call are however set up as normal with allocated resources and speech paths in the BSC and the MSC or the Media Gateway. When STN has identified that two call legs form a call and that the two call legs use the same speech codec the speech frames will be switched locally in the STN node instead of sent to the BSC. This will reduce the amount of bandwidth required for Abis Upper.
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GSM BSS Integration for Field Maintenance
17
Speech path for a locally switched call Speech
Speech path connected locally
20
Signaling
MSC
STN
BSC
M
MSC
O
Unused speech paths
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Figure 3-23: A-bis Local Connectivity (ALC)
It is only possible to identify which two call legs that belong together during call setup. If two call legs end up in the same STN due to that one of them makes a handover into the STN where the other mobile is connected it is not possible to identify that the two call legs belong together and local switching cannot be used for that call. This means that a coexisting WCDMA network can cause Abis Local Connectivity to be less efficient if call setups occurs with one or both mobiles in the WCDMA network and the call is then handed over to the GSM network.
IO
For locally switched calls there are almost no speech frames sent on Abis upper between the BSC and the STN node. Local switching is initiated when the B end answers the call, and before that speech frames are sent as normal. There are also some speech frames transmitted during each handover. All signaling messages are transmitted on Abis as usual.
ET H
Speech frames for calls that are not being locally switched are sent through the network exactly as normal.
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STN can only locally switch a call if both call legs use the same speech codec. In order to increase the chance that the Calling Party and the Called Party ends up using the same speech codec two different methods can be applied. Using the first method the BSC will during channel allocation in Abis Local Connectivity cells prefer to use the same codec to all calls. The preferred codec is chosen from the set of EFR, FR and HR. If an allocation of the preferred codec fails for whatever reason the call will be setup using another codec if possible. The second method is based on letting the STN node manipulate the call setup signaling, more specifically to manipulate the bearer capability parameter describing the codec capability of the Calling respective the Called Party. The codec capability of respective party is aligned to a common list of codecs supported by both parties and finally aligned to a preferred codec list configured in the STN node.
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17
The Abis Local Connectivity feature can be run in two modes, enable or monitor mode. In enable mode the STN node identifies which call legs that form a call and switches speech frames locally when it serves both legs of a call and the two call legs use the same speech codec.
20
With Abis Local Connectivity in monitor mode local calls are identified without requiring the two call legs to use the same codec. No traffic is locally switched, but counters are updated as if identified calls were locally switched. Monitor mode is a tool to analyze the amount of local calls and help dimensioning for Abis Local Connectivity.
M
For Abis Local Connectivity to work it is vital that the addition it makes to the call setup signaling is transferred transparently through the core network.
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The STN hardware implementations supporting Abis Local Connectivity is the SIU and the RBS 2409.
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GSM BSS Integration for Field Maintenance
Air Interface
3
2
1
M
20
The air interface uses the Time Division Multiple Access (TDMA) technique to transmit and receive traffic and signaling information between the RBS (BTS) and MS. The TDMA technique is used to divide each carrier into eight timeslots. These timeslots are then assigned to specific users, allowing up to eight conversations to be handled simultaneously by the same carrier.
1
2
3
4
7
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0
Downlink
0
5
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Uplink
6
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TDMA Frame
6
7
Time slot
TDMA Frames are serially numbered from 0 to 2,715,648
Frame No. 3754
Frame No. 3755
Frame No. 3756
Frame No. 3757
Figure 3-24: Air Interface
The physical content of a timeslot is called a “burst”.
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The following sections describe the functional characteristics of the Air interface.
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17
Frequency Bands Frequency
GSM 800
GSM 900
GSM 1800
GSM 1900
Uplink
824-849 MHz
890-915 MHz
1710-1785 MHz
1850-1910 MHz
Downlink
869-894 MHz
935-960 MHz
1805-1880 MHz
1930-1990 MHz
ARFCN Range
128 to 251
512 to 885
512 to 810
P-band: 1 to 124
20
8.1
G1-band: 0 and 975 to 1023
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Figure 3-25: Frequency Bands and ARFCN
M
ARFCN = Absolute Radio Frequency Channel Numbers
Characteristics of frequency bands in the GSM system include:
“Over-the-air” bit rate of 270 kbps Duplex distance of 45 MHz (GSM 900), 95 MHz (GSM 1800) or 80 MHz (GSM 1900) Channel separation of 200 kHz Gaussian Minimum Shift Keying (GMSK)-type modulation used
TE LE C
NOTE: ARFCN is the pre-established Absolute Radio Frequency Channel Number range for each of the different GSM bands. There is a defined ARFCN for every 200 kHz of the frequency range. 849 MHz
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824 MHz
Uplink
869 MHz
Unlicensed
ET H
824.2
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894 MHz Downlink
869.2
824.4
869.4
824.6
869.6
ARFCN
Uplink
Downlink
128
824.2
869.2
129
824.4
869.4
130
824.6
869.6
Channel Separation = 200 kHz
Figure 3-26: Uplink and Downlink for GSM 800 Band
© Ericsson AB 2012
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GSM BSS Integration for Field Maintenance
Air Interface Channels
20
Each ARFCN supports eight BPCs (or Basic Physical Channels) as seen in figure below.
Cell X 512
M
524
Example: 2+1+1 Three-Sector Site
16 BPCs
516
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520
BPC = Basic Physical
Cell Y
O
Cell Z
8 BPCs
8 BPCs
Channels
Each ARFCN supports eight (8) BPCs
Figure 3-27: Example of ARFCNs and BPCs
ET H
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The path used to carry information between an MS and a BTS is known as the Physical Channel. The information carried on the Physical Channels is classified according to Logical Channels.
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Logical Channels
Cell X
Cell Z
Cell Y
Broadcast Channels
8 BPCs
Common Control Channels
Dedicated Channels
M
8 BPCs
Control Channels
20
Traffic Channels
16 BPCs
17
Physical Channels
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Figure 3-28: Air Interface Channels
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The path used to carry information between an MS and an RBS is known as the Basic Physical Channel. The information carried on the Physical Channels is classified according to Logical Channels.
The Logical Channels are divided into two categories – Traffic Channels (TCHs) and Control Channels (CCHs). The Traffic and Control Channels are further subdivided; there are three types of Traffic Channels and three categories of Control Channels with a total of nine different types.
8.2.1
Traffic Channels (TCHs)
TCHs carry either speech or data. There are two types of traffic channels: Full Rate (FR) and Half Rate (HR). The TCH can be located in any timeslot on any frequency defined in the cell, except for the first timeslot (TS0) on the first carrier (C0).
ET H
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Full Rate (FR) – The Full Rate Traffic Channel (TCH/F) handles encoded speech or data. The TCH information is transmitted at a gross rate of 22.8 kbps. Enhanced Full Rate (EFR) provides a slight improvement in the transmission rate of voice (12.2 kbps). Half Rate (HR) – With a Half Rate Traffic Channel (TCH/H), a mobile station will only use every second timeslot (every other one is idle). The TCH information is transmitted at a gross rate of 14.4 kbps. As a result, two mobile stations are able to use the same physical channel for calls, leading to a doubling of the capacity on the channel.
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Logical Channels HR HR
HR HR
FR
FR
Cell Y
FR
FR
M
Half Rate (HR): • 2 conversations can use 1 BPC • 6,5 kbps voice or 4.8 kbps data
HR HR
Cell X
Cell Z Full Rate (FR): • 1 conversation occupies 1 BPC • 13 kbps voice or 14.4 kbps data
HR HR
20
FR
Traffic Channels (TCH)
FR FR
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Enhanced Full Rate (EFR): • 1 conversation occupies 1 BPC • 12.2 kbps voice or 14.4 kbps data
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Figure 3-29: Traffic Channels
The following graphic illustrates an example of FR and HR on a Traffic Channel Multiframe – also known as a 26-Multiframe. The 26-Multiframe has a duration of 120 ms over 26 TDMA frames. Built-in Control Channel
TCH/F
T T T T T T T T T T T T 0 1
2
3
4
5
6
7 8
9
Idle
T T T T T T T T T T T T I
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Full Rate
T0 Burst goes to Subscriber 0
T1 Burst goes to Subscriber 1
T0
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2
T0 T1 3
T0 T1
4
5
T0 T1
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T0 T1
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9
T0 T1
T0 T1
T0 T1
T0 T1
T0 T1
T0 T1
T1
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Half Rate
After 26 frames, this pattern of traffic channels repeats itself. This is called a Traffic Channel Multiframe or a 26-Multiframe. Figure 3-30: Traffic Channel Multiframes
© Ericsson AB 2012
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GSM RAN Interfaces
Adaptive Multi Rate (AMR)
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The Adaptive Multi Rate (AMR) is a speech and channel codec for both HR and FR channels. By adapting the codec rate to the radio conditions, the speech quality is enhanced. At low C/I (a ratio between signal strength and interference signal strength), a large amount of channel coding is applied and less speech coding. When the C/I increases, the speech coding is increased and the channel coding is decreased.
Source Codec Bit Rate 7.40 Kbps 6.70 Kbps 5.90 Kbps
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AMR HR TCH
7
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Channel Mode
M
Both the BTS (uplink) and the MS (downlink) continuously measure the radio quality (C/I). Based on these measurements, the codec rate is changed. AMR requires support in all network nodes, i.e., MSC, BSC, BTS and MS. AMR is only supported in cells where all TRUs are AMR-capable. 6
5
4
3
2
1
0
5.15 Kbps
Burst
4.75 Kbps
12.2 Kbps (GSM EFR) 10.2 Kbps 7.95 Kbps
AMR FR TCH
Speech
Protection
Low Noise Environment – High Speech Quality
7.40 Kbps 6.70 Kbps 5.90 Kbps
High Noise Environment – Low Speech Quality
5.15 Kbps 4.75 Kbps
Speech
Protection
IO
Figure 3-31: Adaptive Multi Rate (AMR)
ET H
8.2.3
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Adaptive Multi Rate WideBand (AMR-WB) Adaptive Multi Rate WideBand (AMR-WB) is a speech and channel codec for full rate GERAN channels and UTRAN defined by 3GPP and ITU-T, with four different codec types. The AMR-WB codec type described in this document is the GERAN GMSK codec type, known as FR_AMR-WB according to the specifications. In this document this codec type will be referred to as AMR-WB. By adapting the codec rate to the radio conditions the speech quality is enhanced. At low C/I, a large amount of channel coding is applied and less speech coding. When the C/I increases the speech coding is increased and the channel coding is decreased.
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17
AMR-WB requires support in all network nodes, that is MSC/MGw, BSC, BTS and MS. AMR-WB is supported when all TRXs within one channel group are AMR-WB capable.
20
It is no longer necessary to have support for AMR-WB in the whole cell or subcell. The BSC can now set up AMR-WB as soon as all TRXs within one channel group support AMR-WB.
The feature AMR-WB offers a significant improved speech quality compared to the previously existing codecs.
M
AMR-WB is supported on TRA R6, TRA R6B and TRA R7 and by all PPCbased transceivers.
O
For GMSK modulation only the three lowest modes, 6.6, 8.85 and 12.65 kbps are allowed.
TE LE C
The bandwidth of the analogue input and output signal for AMR-WB will range from 100 Hz to 7000 Hz (for narrowband codecs the bandwidth used range from 300 Hz to 3400 Hz). The extended lower spectrum brings volume and quality while the extended higher spectrum brings clarity and transparency to the speech signal. Together it provides a well-balanced speech signal with substantially higher quality. Since there is no PCM encoding standard for AMR-WB the speech must be sent compressed throughout the network. This is achieved by means of Tandem Free Operation (TFO) and Transcoder Free Operation (TrFO) for both 2G and 3G networks. As a consequence, all nodes involved in an AMR-WB call from one subscriber to another, must have support for AMR-WB, that is MSs, BTSs, BSCs, MGws and MSC servers.
IO
TFO avoids transcoding the speech but needs the transcoder hardware in the path, while TrFO does not have the transcoder hardware in the path.
ET H
A new transcoder pool is added to group all AMR-WB capable transcoder resources for TFO. This new pool will coexist with the previously existing pools.
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For AMR-WB, that use TFO and TrFO to transport the digitally encoded speech, the optimal codec mode must be suitable to both radio channels, the local uplink and the distant downlink radio channel and vice versa. The channel with the highest error rate (or smallest capacity) determines the highest possible codec mode. The codec mode used in one direction may however be different from the one used in the other direction.
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20
17
The principle for codec mode adaptation in TFO and TrFO mode is simple. The radio receivers (for example the local uplink BTS receiver and the distant downlink mobile receiver) estimate the observed radio quality and determine the optimal codec mode. The final codec mode to be used is achieved by taking the minimum of both. The distant mobile sends therefore its codec mode request uplink and this is transferred all the way back to the local BTS. The local BTS takes the minimum of the distant codec mode request and its local codec mode decision and sends the result downlink to the local mobile to be used on the local uplink. The result is also sent to the distant BTS. The selected codec mode will now also be used on the distant downlink radio channel.
O
M
This mechanism works symmetrically, but independently in both directions of the speech conversion. This means that the codec mode used in one direction can be different to the codec mode used in the other direction.
TE LE C
The codec set to be used for AMR-WB, together with decision thresholds and hysteresis values, is sent from the BSC to the BTS and MS at setup and handover. In Ericsson BSS only one codec set for AMR-WB is supported, it’s presented bellow.
•The feature AMR-WB offers a significant improved speech quality compared to the previously existing codecs. •By adapting the codec rate to the radio conditions the speech quality is enhanced. •The bandwidth of the analogue input and output signal for AMR-WB will range from 100 Hz to 7000 Hz . • The extended lower spectrum brings volume and quality •The extended higher spectrum brings clarity and transparency to the speech signal.
ET H
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Code Set
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Source Codec Bit Rate
AMR WB
CODEC_MODE_1
6.60 kbps
CODEC_MODE_2
8.85 kbps
CODEC_MODE_3
12.65 kbps
Figure 3-32: AMR-WB Codec Set
The decision threshold and hysteresis values are settable with the MML command RLADC.
© Ericsson AB 2012
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GSM BSS Integration for Field Maintenance
Control Channels (CCHs)
17
8.2.4
20
CCHs carry signaling information used by the MS to locate an RBS, synchronize itself with the RBS, and receive information required to perform call setup. There are three categories of control channels: Broadcast Channels (BCHs), Common Control Channels (CCCHs), and Dedicated Control Channels (DCCHs).
Traffic Channels
O
Control Channels
M
Logical Channels
Common Control Channels (CCCH)
TE LE C
Broadcast Channels (BCH)
Dedicated Control Channels (DCCH)
Figure 3-33: Control Channels
8.2.5
Broadcast Channels (BCHs)
All BCHs are transmitted point to multi-point over the downlink. The three BCHs include:
ET H
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Broadcast Control Channel (BCCH) – Used to broadcast general information to all mobile stations. Some of the information sent on the BCCH is: Band used, ARFCNs used in the cell Frequencies to measure in idle mode, Network Color Codes (NCCs) permitted, Cell Global Identity (CGI), Periodic Update timer, Discontinuous Transmission used on uplink, Discontinuous Transmission used on downlink, Minimum Received Signal Strength for Access, etc
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GSM RAN Interfaces
Broadcast Channels (BCH)
Broadcast Control Channel (BCCH): Broadcasts system information (DL)
›
O
›
17
Control Channels
20
Traffic Channels
› › › › › › ›
M
Logical Channels
Some of the information sent on the BCCH: Band used (GSM 800, 900, 1800, 1900) ARFCNs used in the cell Frequencies to measure in idle mode Network Color Codes (NCCs) permitted Cell Global Identity (CGI) Periodic Update timer Discontinuous Transmission used on uplink Discontinuous Transmission used on downlink Minimum Received Signal Strength for Access
Figure 3-34: Broadcast Channels: BCCH
Frequency Correction Channel (FCCH) – Provides the frequency correction information used by the mobile station. Indicates which carrier – typically Carrier 0 (C0) – the BCHs are on.
TE LE C
Logical Channels
Traffic Channels
The FCCH: › Indicates which carrier – typically Carrier 0 (C0) – the BCHs are on › Allows the MS to synchronize to the correct BCH frequency
Control Channels
Broadcast Channels (BCH)
IO
Broadcast Control Channel (BCCH): Broadcasts system information (DL)
Frequency Correction Channel (FCCH): Unmodulated sine wave (all zeroes) (DL)
ET H
Figure 3-35: Broadcast Channels: FCCH
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Synchronization Channel (SCH) – Contains the Base Station Identity Code (BSIC) and the TDMA frame number used for synchronization of the mobile station to the frame structure of a new BTS.
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NCC
BCC
Network Color Code
Base Station Color Code
3 bits
3 bits
20
Control Channels
Broadcast Control Channel (BCCH): Broadcasts system information (DL) Frequency Correction Channel (FCCH): Unmodulated sine wave (all zeroes) (DL) Synchronization Channel (SCH): Broadcasts the BSIC and TDMA Frame Number (DL)
M
Broadcast Channels (BCH)
› Over the SCH, the MS synchronizes to the time structure within a particular cell › The SCH broadcasts the TDMA Frame Number and the Base Station Identity Code (BSIC): The BSIC is made up of two digits – each between 0 and 7 The first digit is the Network Color Code (NCC) The second digit is the Base Station Color Code (BCC)
O
Traffic Channels
17
Base Station Identity Code (BSIC) Logical Channels
8.3
TE LE C
Figure 3-36: Broadcast Channels: SCH
Base Station Identity Code (BSIC)
The Base Station Identity Code (BSIC), transmitted over the SCH, is made up of two 3-bit digits, each between 0 and 7. The first digit is the Network Color Code (NCC), and the second digit is the Base Station Color Code (BCC). This number is expressed as NCCBCC in command language, for example, 07 or 26.
ET H
IO
If the MS can detect the synchronization burst (on the SCH) and decode the BSIC, it first checks if the first number, the NCC, is permitted. NCCs are established along network borders to prevent accidental handovers between two different network providers.
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Network Border
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Network B NCC = 5
20
Network A NCC = 6
17
GSM RAN Interfaces
TE LE C
› At a network border, the two operators must agree on differing NCCs to prevent accidental handover attempts. › Within the borders of the network, the NCC is not significant.
Figure 3-37: Network Color Code (NCC)
BCC=0 BCC=1 BCC=2
ET H
IO
BCC=3
8.3.1
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BCC=4 Typical BCC allocation for cells within a network
BCC=5 BCC=6 BCC=7
Figure 3-38: Base Station Color Code (BCC)
Control Channel Multiframe Where traffic channels are carried over Traffic Channel Multiframes (26Multiframe), control channels – and specifically BCHs – are carried over Control Channel Multiframes. A Control Channel Multiframe is made up of 51 TDMA frames and has a duration of 235.4 ms.
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TS0 C0 DL
11
F S B B B B
F S
21
31
F S
F S
41
51
FCCH
S SCH B B B B
BCCH (large amount of information requires 4 bursts)
TE LE C
I Idle
After 51 Frames, the pattern of Control Channels repeats itself. This is called a Control Channel Multiframe.
O
F
I
M
F S
20
Frame Number = 1
17
Illustrates the configuration of BCHs on the Control Channel Multiframe.
Figure 3-39: Broadcast Channels on a BPC
8.3.2
Common Control Channels (CCCHs)
All Common Control Channels are transmitted point to point. There are three CCCHs:
Paging Channel (PCH) - Used to page the mobile station. PCH information is transmitted over the downlink. The International Mobile Subscriber Identity (IMSI) and the Temporary Mobile Subscriber Identity (TMSI) are broadcast to every cell in the Location Area.
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GSM RAN Interfaces
Common Control Channels (CCCH)
•By adding up to 3 new CCCH channels, the paging capacity, will be increased with up to 300%.
20
Control Channels
•The bundling of paging will reduce the CPU load from paging by around 70% . •Multiple CCCH is an optional feature and is activated/deactivated per cell.
Paging Channel (PCH): Broadcasts IMSI/TMSI to all cells in Location Area (DL)
M
BCH
•Multiple CCCH makes it possible to allocate up to 4 timeslots containing CCCH channels on the BCCH carrier.
O
Traffic Channels
17
Multiple CCCH Logical Channels
8.3.3
TE LE C
Figure 3-40: Common Control Channels: PCH and Multiple CCCH
Multiple CCCH
Multiple CCCH makes it possible to allocate up to 4 timeslots containing CCCH channels (paging, immediate assignment and Random Access) on the BCCH carrier. The new CCCH channels are placed on TN2, TN4 and TN6. On each timeslot there are 9 CCCH blocks defined. By adding up to 3 new CCCH channels, the paging capacity, the capacity for Immediate Assignments and the capacity for Channel requests will be increased with up to 300%. This will lead to less lost pages and a network that can handle the new more demanding paging traffic.
ET H
IO
The load from handling paging commands in the TRH is normally quite large. With Multiple CCCH the paging rate in the BSC can be increased with up to 300%. This will have a large impact on the TRH capacity. To solve this problem Paging Commands are bundled and sent in one LAPD I frame on Abis. Up to 10 pages can be bundled in one LAPD I frame, where redundant information and unnecessary header information are removed. This new bundling is used for all TRXs which are Multiple CCCH capable, regardless if the feature is activated or not in the network.
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The bundling of paging will reduce the CPU load from paging by around 70% and the link load on Abis from paging commands will be reduced to less than half. It is not recommended to put EDGE traffic on channel group 0 if Multiple CCCH is used. The reason is that the number of consecutive timeslots for EDGE traffic is limited by the CCCH channels.
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GSM BSS Integration for Field Maintenance
17
When Multiple CCCH is configured in the cell the SDCCH/8 can not be put on TN2, 4 or 6 on the BCCH TRX if 4 CCCHs are configured. Instead of the default value to put SDCCH/8 on TN2, it is recommended to put SDCCH/8 on any other TN than Multiple CCCH is using if the SDCCH/8 shall be put on BCCH TRX.
20
When the feature Multiple CCCH is activated, timeslots 2, 4 and 6 may be used in addition to timeslot 0 for the common control channels. The same frequency is used for all CCCHs. An MS shall, using its IMSI as input, calculate which timeslot to use for random access and paging.
IMSI/TMSI
TE LE C
8.3.4
O
M
Multiple CCCH is an optional feature and is activated/deactivated per cell. The number of CCCH channels is specified by the cell parameter CCCH. The feature Multiple CCCH is enabled if the value of the parameter CCCH is 2,3 or 4. When the number of CCCH channel is increased, the channels are configured on the time slot 2, 4 and 6 in ascending order.
Each mobile station has a unique, fixed mobile identifier number, known as the IMSI. When a page is sent over the PCH to locate a particular mobile subscriber, the IMSI is the number used. International Mobile Subscriber Identity (IMSI) Maximum 15 Digits
3 digits
MCC Mobile Country Code
2 or 3 digits
MNC Mobile Network Code
MSIN Mobile Station ID Number
National MSI
ET H
IO
Temporary Mobile Subscriber Identity (TMSI)
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› One IMSI per subscriber › Operator may use TMSI instead: • TMSI adds subscriber security as an alternative to transmitting IMSI • TMSI maximum length is 8 digits, allowing added paging capacity • TMSI changes with each transaction (call, update, attach, etc.) • TMSI is only valid within VLR • Will be used unless Location Update fails or Subscriber Identity Module (SIM) has no allocated TMSI
Figure 3-41: IMSI/TMSI
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Location Area Identity 310-550-22
Location Area Identity 310-55-12
20
Location Area Identity 310-55-21
Location Area Identity 310-55-11
Location Area Identity 310-55-23
Location Area Identity 310-55-24
M
MSC/VLR
17
GSM RAN Interfaces
IMSI
Attached? Yes
O
310-250-21-213213
Location Area 310-550-22
TE LE C
› When a call is made to an MS, the VLR looks up the IMSI in its database › The MSC then sends the paging message to all the cells in the Location Area › All the cells broadcast the Page
Figure 3-42: Paging on the PCH
Random Access Channel (RACH) - Used by a mobile station to request access to the system. RACH information is transmitted over the uplink.
ET H
IO
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GSM BSS Integration for Field Maintenance
Common Control Channels (CCCH)
O
BCH
Control Channels
M
Traffic Channels
20
Logical Channels
TE LE C
Paging Channel (PCH): Broadcasts IMSI/TMSI to all cells in Location Area (DL) Random Access Channel (RACH): MS access request. Uses short bursts (UL)
Figure 3-43: Common Control Channels: RACH
Access Grant Channel (AGCH) - Used to assign a Standalone Dedicated Control Channel (SDCCH). AGCH information, including Timing Advance (TA) and assigned channel number, is transmitted over the downlink.
ET H
IO
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GSM RAN Interfaces
Common Control Channels (CCCH)
O
BCH
Control Channels
M
Traffic Channels
20
Logical Channels
TE LE C
Paging Channel (PCH): Broadcasts IMSI/TMSI to all cells in Location Area (DL) Random Access Channel (RACH): MS access request. Uses short bursts (UL) Access Grant Channel (AGCH): Sends TA and channel for call setup (DL)
ET H
IO
Figure 3-44: Common Control Channels: AGCH
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PCH (I/TMSI)
AGCH TA and Ch #
AGCH TA and Ch #
RACH
RACH
MS Originated Call (Call from MS)
MS Terminated Call (Call to MS)
Figure 3-45: Call Setup Using CCCHs
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GSM BSS Integration for Field Maintenance
BCH and CCCH Carriers
C0
512
marks the timeslot where the BCHs and CCCHs are transmitted.
C1
524
Cell Z
Cell Y
M
C0 = BCCH carrier C1 = TCH carrier
20
Cell X
C0
C0
516
TE LE C
O
520
Figure 3-46: BCH and CCCH Carriers
8.3.5.1
Dedicated Control Channels (DCCH)
All Dedicated Control Channels (DCCHs) are transmitted point to point over both the downlink and the uplink. There are three types of DCCH:
Stand-alone Dedicated Control Channel (SDCCH) – Carries signaling information during call setup.
IO
Logical Channels
ET H
Traffic Channels
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BCH
Control Channels
CCCH
Dedicated Control Channels (DCCH)
TA = 13 Go to SDCCH #5 on C0-TS1 to setup call
Stand-alone Dedicated Control Channel (SDCCH): Used for call setup, registrations, and SMS idle mode transmission
Figure 3-47: Dedicated Control Channels: SDCCH
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GSM RAN Interfaces
Slow Associated Control Channel (SACCH) - Transmits call control data and measurement reports. The MS sends measurement reports, and the RBS sends the MS system information containing instructions regarding the transmit power to use and TA.
Fast Associated Control Channel (FACCH) - Carries urgent signaling information. The FACCH is used when a handover is performed, and works in “stealing mode” – meaning, speech and data are replaced with urgent signaling.
Logical Channels
FACCH/F
+
SACCH/TF
Idle
O
+
Control Channels
Any TCH T T T T F F F F T T T T A T T T T T T T T T T T T I
TE LE C
Traffic Channels
TCH H/F
M
20
17
BCH
CCCH
Dedicated Control Channels (DCCH)
Stand-alone Dedicated Control Channel (SDCCH)
Slow Associated Control Channel (SACCH): MS sends measurement reports (UL). RBS sends the MS system information containing instructions on the transmit power to use and TA (DL). Fast Associated Control Channel (FACCH): Used when a handover is performed. Works in stealing mode, meaning that speech and data are replaced with urgent signaling (DL).
Figure 3-48: SACCH and FACCH
IO
NOTE: Both FACCH and SACCH messages, along with traffic channels, are carried over 26-multiframes.
ET H
8.3.5.2
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Traffic Case: Call to an MS The major difference between a call to an MS and a call from an MS is that in a call to an MS the exact location of the mobile subscriber is unknown. Therefore, the MS must be located using paging before a connection can be established. Below is the description of the call set-up to an MS.
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GSM BSS Integration for Field Maintenance
Radio resource setup on CCCHs
20
17
Immediate Assignment: Go to SDCCH #5 on C0-TS1 to setup call
512 524 536 548
Call setup signaling on SDCCH (or TCH)
O
M
Assignment Command: Go to FR-TCH on C2-TS4 for traffic
Actual traffic on TCH
512 524 536 548
TE LE C
Figure 3-49: Anatomy of a Call Setup
1- The MSC/VLR knows which LA the MS is located in. A paging message is sent to the BSCs controlling the LA. 2. The BSCs distribute the paging message to the RBSs in the desired LA. The RBSs transmit the message over the air interface using PCH. To page the MS, the network uses an IMSI or TMSI. 3. When the MS detects the paging message, it sends a request on RACH for a SDCCH. 4. The BSC provides a SDCCH, using AGCH.
5. SDCCH is used for the call set-up procedures. All signaling preceding a call takes place over SDCCH. This includes: Marking the MS as “active” in the VLR
The authentication procedure
The start of ciphering
Equipment identification
ET H
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6. The MSC/VLR instructs the BSC/TRC to allocate an idle TCH. The RBS and MS are told to tune to the TCH. The mobile phone rings. If the subscriber answers, the connection is established.
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Ericsson RBS Overview
O
Objectives
M
20
4 Ericsson RBS Overview
TE LE C
Identify the RBS 2000 and 6000 series nodes, their functionalities, capabilities and structure, using the student material and checking physically in the available BTS: › Explain the RBS architecture and functional blocks › Differentiate various RBS 2000 and 6000 family units › List the Replaceable Units (RUs) in the RBS 2000 and RBS 6000 › Explain the concept of remote OMT and OMT over IP
ET H
IO
Figure 4-1: Objectives
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1
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GSM BSS Integration for Field Maintenance
Introduction
20
The purpose of this chapter is to give an overview of the RBS 2000 series. The RBS 2000 series is Ericsson’s second generation of radio base stations, developed to meet the GSM specification for BTSs. NOTE: Many of the overhead slides in the instructor’s presentation will not appear in this book.
O
M
The RBS 2000 product family is specially designed to offer rapid and costeffective rollouts, and low total life-cycle costs. In addition, there is simple installation with on-site testing and commissioning. These can be done easily thanks to the cabinets being pre-assembled, and the software being downloaded and tested at the factory prior to shipment. › RBS hardware comprised of Replaceable Units (RU) and various buses.
TE LE C
Y
L I N K
ESB (TG Sync)
Antenna
dTRU
CDU
CDU Tx Control Bus
X
dTRU
› An RU is the smallest hardware part that can be replaced when performing site repairs.
External Alarms (16)
OMT Interface
dTRU
› Transceiver Units (TRUs), cables, and fans, for example, can be considered RUs.
PCM A PCM B
dTRU
Antenna
C dTRU X
DXU 21
CDU
X
U
Antenna
PCM C PCM D
CDU
X
dTRU
IO
IOM Bus
Figure 4-2: RBS 2000 Architecture
ET H
NOTE: Figure 4-2 depicts a RBS 2206 configuration.
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RBS 2000 Architecture
2.1
Replaceable Units (RU)
20
2
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Ericsson RBS Overview
O
M
Before discussing the various RBS 2000 models, it is important to understand several hardware features of this series. The RBS 2000 hardware comprises a number of Replaceable Units (RUs) and buses, which are briefly described in the next sections. The RU is the smallest hardware part that can be replaced when repairs are being done at the site. The RU may be a Transceiver Unit (TRU), cable, fan, etc.
TE LE C
RU
Main RU
Central Main RU
Sub RU
Passive RU
Distributed Main RU
Indirect Distributed Main RU
IO
Direct Distributed Main RU
ET H
Figure 4-3: Replaceable Units (RUs)
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17
Sub RUs Passive RUs
BFU
Central Main RU
PSU
TRU
Cooling Unit Heating Unit
M
DXU
Distributed Main RUs
20
Fan Unit
CDU
O
Cables
TE LE C
CXU
Figure 4-4: RU Type Assignments
2.2
Distribution Switch Unit (DXU)
The Distribution Switch Unit (DXU) is the RBS central control unit. There is one DXU per RBS. It provides a system interface by cross-connecting either a 2 Mbps (E1) or 1.5 Mbps (T1) transport network and individual timeslots to their associated transceivers. In the RBS 2308, 2309, 2108, and 2111, the Interface and Switching Unit (IXU) has the same functionality as a DXU.
ET H
IO
› Interface to BSC via Abis interface › Distributes speech or data, signaling and software to Transceiver Units (TRUs) › Provides a system interface by cross-connecting either 2 Mbps (E1) or 1.54 Mbps (T1) transport networks and individual timeslots to their associated TRUs › Responsible for synchronization of TRUs (Timing Function) › Interface for external alarms (16) › Connection point for Operation and Maintenance Terminal (OMT) › Prepared for EDGE › Contains backup software and Installation DataBase (IDB) in a FLASH CARD memory (non-volatile) › Interface for TG Sync › Supervises the Energy and Environment Equipment
EPC Bus ESB (TG Sync) External Alarms (16) OMT Interface
Y DXU 21
L I N K
PCM A PCM B PCM C PCM D
IOM Bus
Figure 4-5: Distribution Switch Unit (DXU)
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Ericsson RBS Overview
Installation Database (IDB)
M
20
The Installation Database (IDB) is contained within the DXU in FLASH memory or in a FLASH CARD memory and includes: serial numbers for all RUs in the RBS, configuration data of cells supported by the site, Terminal Endpoint Identifiers (TEIs) of the DXU and TRUs, RBS software revisions of main RUs, and external alarms. (TEIs will be further discussed in Chapter 7)
IDB
O
Contained within the DXU in FLASH memory and includes: › Serial numbers for all RUs in the RBS
TE LE C
› Configuration data of cells supported by site › Terminal Endpoint Identifiers (TEIs) of DXU and TRUs › RBS software revisions of Main RUs (e.g., DXU and TRUs) › External alarms
Figure 4-6: Installation Database (IDB)
Operation and Maintenance Terminal (OMT)
ET H
IO
2.2.2
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The OMT is a Personal Computer (PC)-based program that allows RBS technicians the ability to install, diagnose, and repair RBS equipment. Typically, OMT is used by the technician at the site, but it can also be set up remotely from the BSC. Using the OMT, a technician can:
Configure the RBS (create and/or configure the IDB) View the RBS configuration through a graphic display View the contents of the IDB Read measures such as voltages, currents, and transmitter output power throughout the RBS
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17
Search for faulty RUs Reset the RBS
› A PC-based program that allows RBS technicians to install, diagnose, and repair RBSs
20
OMT
M
› Typically used by technicians at the site, although it can be set up remotely from the BSC › Among other things, OMT can:
Graphically display the RBS configuration
›
Display the contents of the IDB
›
Read voltages, currents, transmitter output power, etc. throughout the RBS
TE LE C
O
›
›
Search for faulty RUs
›
Reset the RBS
Figure 4-7: Operation and Maintenance Terminal (OMT)
2.2.2.1
Buses
There are four buses present in most of the RBS 2000 models (with some exceptions noted). These include:
IO
ET H
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Local Bus – Offers internal communication between the DXU, TRUs, and ECU. Examples of information sent on this bus are TRX Signaling, speech and data. Not present in 2106/2206/2207. Timing Bus – Carries air timing information from the DXU to the TRUs. Not present in 2106/2206/2207. X-bus - carries speech/data on a timeslot basis between the TRUs. This is used for base band frequency hopping. Not present in 2106/2206/2207. CDU Bus - Connects the CDU to the TRUs, and facilitates interface and O&M functions, e.g., transfers alarms and RUspecific information. In the RBS 2X06, 2X07, and 2112, the CDU bus is composed of two different buses: CDU TX Control Bus, responsible for VSWR measurements, and IOM Bus,
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Ericsson RBS Overview
2.2.2.2
17
20
responsible for supervision and configuration of the CDU. Not present in 2X16. Y Link - Offers internal communication between the DXU and TRUs. Examples of information sent on this bus are TRX Signaling, speech or data and synchronization. Not present in 2X02.
Energy Control Unit (ECU)
TE LE C
O
M
The ECU controls and monitors the power and climate equipment to regulate the power and the environmental conditions inside the cabinet to maintain system operation. It communicates with the DXU over the Local Bus. The main units of the power and climate system are the PSUs, BFU with batteries, AC Connection Unit (ACCU), Climate Control Unit (CCU), heater, active cooler, and heat exchanger (outdoor cabinets only), Fan Control Unit (FCU), and climate sensors (for temperature and humidity). As mentioned earlier, there is no separate ECU in the RBS 2X06, 2112, 2X16, or 2X07 models. ECU functionality is incorporated in the DXU-21 model.
2.2.2.3
Transceiver Unit (TRU)
ET H
IO
The TRU is a transmitter/receiver and signal-processing unit, which broadcasts and receives the radio frequency signals that are passed to and from the mobile station. Each TRU handles eight air timeslots. In the RBS 2X06, 2X07, and 2112 cabinets, the TRU is a double or dual TRU (dTRU). In the RBS 2X16 the dTRU is called DRU.
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(dTRUs)
–
two
17
› Double (or Dual) TRUs transceivers in one unit
dTRU
› Transmitter/receiver to mobile station (MS) and signal processing in the RBS › Has its own software in FLASH memory (nonvolatile)
Y
dTRU
L I N K
dTRU
M
› Can serve 8 full-rate duplex channels (air timeslots) per TRU
20
› Includes power amplifier
dTRU
dTRU
O
› One transmitter output and two receiver inputs (for receive diversity)
dTRU
› Function for Radio Frequency (RF) test loop for assessing transmit and receive properties
2.2.2.4
TE LE C
Figure 4-8: Transceiver Unit (TRU)
Combining and Distribution Unit (CDU)
A combiner is a device, at the base station, that allows for the connection of several transmitters to one antenna. It allows each transmitter RF energy out to the antenna, while blocking the RF energy from other transmitters utilizing the same antenna. Two combiner types are Hybrid and Filter.
› Interface between the TRUs and the antennas
Antenna
CDU
X
IO
› Allows several TRUs to share antennas
ET H
› Protects TRUs and provides feedback and fault information
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Antenna
CDU
X
› May require external duplexors › Two combiner types: Hybrid and Filter
Antenna
› Seven versions include A, C, C+, D, F, G and J CDU
X
Figure 4-9: Combining and Distribution Unit (CDU)
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Ericsson RBS Overview
Configuration Switch Unit (CXU)
20
The task of the Configuration Switch Unit (CXU) is to cross-connect the CDU and the dTRU in the receiver path. The CXU makes it possible to expand or reconfigure a cabinet without moving or replacing any RX cables.
M
The RX inputs/outputs on the dTRU and the CDU are placed in such positions that they minimize the number of cable types used to connect the CXU to the dTRUs and the CDUs.
O
› Cross-connects the CDU and the dTRU in the receiver path.
TE LE C
› Makes it possible to expand or reconfigure a cabinet without moving or replacing any RX cables. › Minimizes the number cable types used to connect the CXU to the dTRUs and the CDUs.
C X U
› Software configured.
IOM Bus
ET H
IO
Figure 4-10: Configuration Switch Unit (CXU)
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GSM BSS Integration for Field Maintenance
Power Supply Unit (PSU)
O
M
20
The purpose of the PSU is to rectify the incoming AC power to the regulated Direct Current (DC) voltage required by the RBS. The PSU communicates with the DXU, handles alarms, adjusts voltages accordingly, and power limitations as needed.
TE LE C
› Rectifies the incoming Alternating Current (AC) power to the regulated Direct Current (DC) voltage required by the RBS › Communicates with the DXU via EPC Bus › Handles alarms › Adjusts voltage
› Provides power limitation
Figure 4-11: Power Supply Unit (PSU)
2.2.2.7
Battery Fuse Unit (BFU)
ET H
IO
The Battery Fuse Unit monitors and controls the battery. It cuts off the load to the RBS at low battery voltage, when the temperature of the battery is too high or if there is a short circuit between the distribution cables.
- 108 -
The BFU supplies battery backup system voltage to the RBS and disconnects the battery when it has reached its lower discharge limit. The contactor can disconnect and reconnect the battery with a control signal from the Supervision Module (SM). The Battery Fuse Unit supervises the connection or disconnection of the batteries.
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RBS 2000 Family
3.1
The updated RBS 2106 V3 DXU-23
M
New IDM
20
3
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Ericsson RBS Overview
X
O
New highpower PSUs
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1500W each
More: • New BFU-32 • FCU removed • OXU positions removed
New Climate unit (Eco Cooling)
Figure 4-12: RBS 2106 V3
Benefits
New high-power PSUs
New DXU
New IDM
New BFU-32
OXU positions removed
FCU removed
New Climate unit (Eco Cooling)
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Impacts
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Compatibility
No impact on BTS SW, OMT is updated. (R10 or later is good)
Product package impact
To differentiate Ordering name is change to “RBS 2106 V3”.
During substitution phase RBS 2106i and RBS 2106 (V3) can be ordered.
Ordering procedure of expansion kits for current RBS 2106 is unchanged.
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Technical Limitations/Restrictions
OXU positions are removed.
Installation Engineering, Installation & Commissioning
No impact.
Spare Parts
Newly introduced units spare parts are required
Spare parts for current RBS 2106 are still orderable.
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Ericsson RBS Overview
The Updated RBS 2206 V2
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ACCU-11/ DCCU-11
CDU-K
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DCCU-13
DXU-23
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New highpower PSUs
1500W each
Figure 4-13: RBS 2206 V2
Benefits
New high-power PSUs
New DXU
New IDM/ACCU/DCCU
AC switch removed
OXU positions removed
FCU removed
No connection field for external cabling
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RBS 2x16
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The RBS 2216/2116 is a high-capacity, high-performance indoor/outdoor base station, and a member of the world leading RBS 2000 product family.
Figure 4-14: RBS 2X16
5.1.1
Benefits
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Complete indoor 12 carrier GSM site on 0,24 m2 foot print
Indoor 24 carriers GSM RBS on 0,24 m2 foot print
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Improved TX output power, fewer sites needed. Fast time to service - improved design for site acquisition and installation. With growing subscriber penetration and growing traffic in the GSM networks, capacity growth is important. In the same time, it is becoming more difficult to find base station sites in appropriate areas or to expanding existing sites. The RBS 2216/2116 addresses both these issues and presents operators with concentrated site build, simplified rollout and flexible configurations. For coverage expansions, the RBS 2216/2116 allows networks to be built with fewer sites, simplified to rollout and reduced cost of operations.
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Ericsson RBS Overview
RBS 2308
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6
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RBS 2308 is the successor to today's micro base station, RBS 2302. The output power and the number of antenna connectors remain the same, but the RBS 2308 will have almost three times the capacity of its predecessor. Despite all new functionality and increased capacity, the size of RBS 2308 will be the same as the RBS 2302.
Benefits 4 carriers per cabinet
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The RBS 2308 is available for the frequencies GSM 800, E-GSM 900, 1800 and 1900 MHz.
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Output power 34 dBm/carrier for GSM 800/900 MHz and 33,5 dBm/carrier for GSM 1800/1900 MHz EDGE and GPRS support No footprint
Both indoor and outdoor
Silent in operation from -33°C to +45°C Easy and fast to install
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Support capacity growth up to 12 TRX (through extension cabinets)
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1 – MBU (1-4) Mounting Base Unit
2 – IXU (1) Interface and Switching Unit
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2A – Flash Memory (1) 2B – TIM (1) Transmission Interface Module
3 – RRU (1-3)
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Remote Radio Unit
4 – Sunshields
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Figure 4-15: RBS 2308
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(1 top, 1 front, 2 side / cabinet)
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Ericsson RBS Overview
RBS 2111
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The RBS 2111 is a medium-capacity indoor and outdoor base station operating in the P-GSM 900, and GSM 1800. It is used for indoor and outdoor applications, with up to three sectors with two carriers per sector. The RBS 2111 is a MainRemote RBS that consists of an outdoor Main Unit (MU) and one to three outdoor Remote Radio Unit-Ns (RRU-Ns).
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› Radio configurations supported on P-GSM 900 and GSM 1800 MHz › Frequency hopping › Two-way RX diversity › Up to four external alarms › EDGE › The RRU-N is mounted close to the antenna › Can be equipped with two E1, 120Ω or 75Ω transport network interfaces › Provides macro coverage and can be configured for 1 - 3 sectors, with 2 carrier per sector
Figure 4-16: RBS 2111
The main features of RBS 2111 are described below:
Radio configurations supported on P-GSM 900 and GSM 1800
Discontinuous transmission/reception
Duplex filters
Supports encryption/ciphering
Dynamic power regulation
Frequency hopping: it is possible for the BTS and MS to hop from frequency to frequency during a call.
Two-way RX diversity: One way to achieve diversity is to use two reception channels that are independently influenced by fading. The probability that both of them are being affected by a deep fading dip at the same time is low.
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External alarms
EDGE
Wide range power input 100 - 250 V AC and -48 V DC
The AC and DC powered RBS 2111 are different products, which are not changeable or upgradeable between each other.
Expansion by Transceiver Group (TG) synchronization
The RRU-N is mounted close to the antenna
Can be equipped with up to 3 RRU-Ns, each with a maximum available output power of 20 W per carrier for P-GSM 900 or GSM 1800, providing macro coverage and can be configured for 1 - 3 sectors, with 2 carrier per sector
Can be equipped with two E1, 120 or 75 transport network interfaces
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RBS 2111 can not support GPS as external synchronization source.
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RRU close to antenna Transmission MiniLink Radio unit
Main Unit Up to three RRU Transmission MiniLink
Figure 4-17: RBS 2111 Hardware infrastructure
RBS 2111 consists of a MU- Main Unit that is responsible for central control function of the RBS and is connected to the RRU-Ns through the Y-Link optical cable. The RRU-Ns provide transmission and reception for the RBS. Some optional units can be used as PDB – Power and Distribution Box and Optional Battery Backup.
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Ericsson RBS Overview
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The Main Unit (MU) is the central control unit of the RBS 2111. It provides the RBS with the interfaces to the transport network through two E1 transmission ports handles incoming traffic, controls and supervises information and sends it to its destination within the RBS.
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RBS 2111 Second Generation
MU-12
RRUN8-22
RRUN9P-22
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And up to three of the following RRU-Ns:
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In this case, the RBS can consist of the following MU:
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The RBS 2111 Second Generation is also a member of the RBS 2000 family, with 6 TRXs for both indoor and outdoor applications. There are a few differences between this new release and the previous like some interfaces and capabilities. In meanings of configuration it is the same.
RRUN9E-22
RRUN18-22
RRUN19-22
The figure bellow shows the main differences for the RBS 2111 Second Generation, the units of measurement are in mm.
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› Supports GSM 800, E-GSM 900, P-GSM 900, GSM 1800 and GSM 1900 › Can be equipped with 2 E1/T1 with 100, 120 or 75 ohms interfaces › Can be equipped with PSUAC kits to adopt AC power
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Figure 4-18: RBS 2111 Second Generation
The distance between MU and RRU-N is limited by the maximum length of the optical fiber connecting the two units, which is 500 m. The RBS 2111 Second Generation supports a length up to 3 km.
© Ericsson AB 2012
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Ericsson RBS Overview
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The hardware units of the RBS 2111 Second Generation are the Main Unit (MU), Remote Radio Unit (RRU-N) and Optical fiber.
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RBS 2409
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RBS 2409 indoor Pico is easily deployed either as stand-alone base station or as driver of a distributed antenna system. The Base Station has a capacity and output power suitable for small offices or public areas. Each RBS 2409 has one TRX built in. Two units can be combined to form a single cell giving triple capacity.
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The small size and weight enables easy site acquisition and quick installation. It can be mounted hanging on a wall close to the ceiling.
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The RBS 2409 is based on the RBS 2000 family radio platform. RBS 2409 supports all of Ericsson’s basic and optional features and provide an Ericssonquality radio environment at low cost.
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Pico to Macro intra-BSC handover and other traffic control functionalities are supported where RBS 2409 shares BSC with Micro and Macro Base Stations. Inter Cell Dependency Matrix (ICDM) is also supported. ICDM is based on actual downlink and uplink interference measurements, which ensures professional automatic frequency and neighbor cell planning.
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Figure 4-19: RBS 2409 Pico STN Function Imbedded
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Ericsson RBS Overview
Ericsson RBS6000 Product Family
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The RBS 6000 product portfolio offers a wide range of solutions ranging from macro base stations to main-remote solutions. This is to provide modularity at the right level and to provide the most cost effective complete site solution for every site need.
RBS 6302
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RBS 6202
RBS 6301
RBS 6201 RBS 6601 RBS 6102 RBS 6101
RRU
AIR (Antenna Integrated Radio)
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Figure 4-20: RBS 6000 Portfolio
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The RBS 6000 solution provides very high capacity for WCDMA (up to 48 WCDMA cell carriers using two radio shelves). If one radio shelf is used for WCDMA, then there is still space for 6 more Radio Units in the second radio shelf that can be used for future LTE introduction and/or GSM modernization.
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The main products available for the RBS6000 family are:
Outdoor macro site (RBS 6102, 6101)
Indoor macro site (RBS 6201)
Main remote site (RBS 6601, 6301)
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One of the main key benefits of the Ericsson solution is the cost effective and complete site solutions in one cabinet.
Figure 4-21: RBS 6000 Product Family True multi standard & mixed mode support
Within RBS 6000 family there are two macro outdoor solutions, RBS 6102 and RBS 6101. RBS 6102 is the first outdoor version that will be released.
RBS 6102
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RBS 6102 is the high capacity outdoor macro RBS and provides a complete and cost effective radio site including transport equipment, site power and battery backup in a single cabinet. The cabinet can house up to two radio shelves and is designed for high capacity single and multi-standard demands.
With a footprint of just 0.9 m2 (1300×700 mm) the RBS is initially able to deliver up to 24 GSM Transceivers (TRXs) using RUG (2 TRXs/RU) or up to 48 GSM TRXs using MCPA based RUS (4 TRXs/RU) with an evolution to support up to 72 TRXs
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Ericsson RBS Overview
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(6TRXs/RU) for GSM. For WCDMA the cabinet can handle up to 48 WCDMA carriers (4 carriers/RU).
10.2
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Besides the mentioned maximum configurations in a single standard configuration, the RBS supports a flexible mix of GSM, WCDMA and LTE radio units.
RBS 6101
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RBS 6101 is the compact outdoor macro RBS. The cabinet houses one radio shelf and has space for power, transport and a short battery backup. RBS 6101 can also be equipped as a high capacity Main Unit for main remote solutions.
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With a footprint of just 0.5 m2 (700×700 mm) the RBS is initially able to deliver up to 12 GSM Transceivers (TRXs) using RUG (2 TRXs/RU) or up to 24 GSM TRXs using MCPA based RUS (4 TRXs/RU) with an evolution to support up to 36 TRXs (6TRXs/RU) for GSM. For WCDMA the cabinet can handle up to 24 WCDMA carriers (4 carriers/RU). Besides the mentioned maximum configurations in a single standard configuration, the RBS supports a flexible mix of GSM, WCDMA and LTE radio units.
10.3
RBS 6201
The RBS 6201 is an indoor macro base station that is part of the nextgeneration,multi-standard RBS 6000 family.
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Employing a simplified cabinet design and an innovative modular building practice, the RBS 6201 integrates a complete high-capacity site into a single cabinet in a very small footprint of 0.24 m2. The cabinet contains two radio shelves and all power, transport network and supporting equipment.
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The RBS is initially able to deliver up to 24 GSM Transceivers (TRXs) using RUG (2 TRXs/RU) or up to 48 GSM TRXs using MCPA based RUS (4 TRXs/RU) with an evolution to support up to 72 TRXs (6TRXs/RU) for GSM. For WCDMA the cabinet can handle up to 48 WCDMA carriers (4 carriers/RU). Besides the mentioned maximum configurations in a single standard configuration, the RBS supports a flexible mix of GSM, WCDMA and LTE radio units.
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GSM BSS Integration for Field Maintenance
RBS 6601
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RBS 6601 is a very small indoor Main Unit (MU) that can be inserted into a standard 19. rack or an existing macro RBS. The RBS provides a solution to very challenging sites when minimal space is available.
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Up to 12 Remote Radio Units (RRUs) can be connected to a MU to match any site requirement. The MU can connect to all types of Remote Radio Units such as RRU22, RRUW as well as RRUS.
Unit Migrations
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RBS 6601 can fit one Digital Unit for WCDMA or two Digital Units for LTE or GSM.
The next picture shows the migration from the existing unit to the system unique Digital Units and Radio Units to the multi-standard software defined units.
GSM
› One Family for all standards, with different radio shelves:
DXU
DRU
WCDMA
PSU
Digital Subrack
RU FU
Digital Unit (G/W/L)
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PSU
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Radio Unit (G/W/L)
Figure 4-22: RBS 6000 CPP units
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Ericsson RBS Overview
Digital Unit for GSM
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The Digital Unit GSM (DUG) can control up to 12 GSM carriers. If more than 12 TRXs are required, then an additional DUG can be installed on the radio shelf and synchronized with the other DUGs in the cabinet. The DUG comes in two variants: DUG 10, which supports RUG, and DUG 20, which supports RUS and RRUS.
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The DUG supports the cross-connection of individual time slots to specific TRXs and extracts the synchronization information from the Pulse-Code Modulation (PCM) link to generate a timing reference for the RBS.
E1/T1 transmission interface
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The DUG supports:
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Baseband processing (DUG 20)
Link Access Procedures on D-Channel (LAPD) concentration / multiplexing
Dual band e.g. 3x2 900 + 3x2 1800 with one DUG
Abis optimization
Multi-drop (cascading)
Synchronized radio network, through an external GPS receiver
Transceiver Group (TG) synchronization
Site LAN
To handle IP, combination with optional equipment such as SIU, MINI-LINK or OMS is recommended.
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20
In the next picture below the layout of the 2 variants of DUGs are shown. There is also a table with the interfaces.
Marking
Interface
Description
Power
Power
-48 V DC
Optical Indicator
GPS
RJ-45
GPS interface including GPS power
EC
RJ-45
Enclosure Control EC-bus common
LMT A
RJ-45
Local Management Terminal A
LMT B
RJ-45
Site LAN and Local Management Terminal B
Yes
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RJ-45
E1/T1 port
Yes
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RJ-45
E1/T1 port
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Fault - Optical indicator, red
Yes
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Operation - Optical indicator, green
Yes
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Maintenance - Optical indicator, blue
Yes
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Status - Optical indicator, yellow
Yes
Button
Maintenance Switch DU mode between Remote and Maintenance
No
ESB
HSIO
For synchronization to other GSM base stations
No
RIA-F
Y-link
Radio Interface A-F including TMA power (electrical)
Yes
No
No
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Yes No
Yes
Figure 4-23: Digital Unit GSM, DUG 10 01Interfaces
Marking
Interface
Description
Optical Indicator
Power
Power
-48 V DC
No
GPS
RJ-45
GPS interface including GPS power
No
EC
RJ-45
Enclosure Control EC-bus common
Yes
LMT A
Local Management Terminal A
No
RJ-45
Site LAN and Local Management Terminal B
Yes
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RJ-45
E1/T1 port
Yes
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RJ-45
E1/T1 port
Yes
-
Fault - Optical indicator, red
Yes
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Operation - Optical indicator, green
Yes
-
Maintenance - Optical indicator, blue
Yes
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Status - Optical indicator, yellow
Yes
Button
Maintenance Switch DU mode between Remote and Maintenance
No
ESB
HSIO
For synchronization to other GSM base stations
No
A-F
CPRI, 6 X SFP
Radio Interface A-F excluding TMA power
Yes
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RJ-45
LMT B
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Figure 4-24: Digital Unit GSM, DUG 20 01Interfaces
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Ericsson RBS Overview
Multi-Standard Radio
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Ericsson is using the definition of Multi-Standard Radio (MSR) where it is possible to use the same HW radio unit for different radio access technologies but within the same frequency band e.g. 850, 900, 1800, 1900 or 2100. Moreover Ericsson MSR with RUS/RRUS is prepared to support mixed mode, i.e. two standards at the same time sharing the same MCPA based power amplifier. The Ericsson MSR radios will be called RRUS and RUS.
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› Multistandard support – GSM, WCDMA and LTE – HW supports for two technologies simultaneously
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The main radio unit for the RBS 6000 family, the RUS, supports multiple technologies, GSM, WCDMA and LTE, and is based on MCPA technology. The specific standard that is supported is defined by the software that is installed on the radio unit. It will also be possible to support two radio technologies simultaneously on one radio unit, sharing the same antenna ports. The exact capabilities for these radio units will be set by its instantaneous bandwidth and the available output power to be shared for all radio carriers and technologies.
RUG (GSM)
› Extremely compact
RUW (WCDMA)
› Output Power @ ARP – 60W on all bands (4x20W on GSM*) › Output power and carrier flexibility – HW activation licenses
RUS (MSR) RUL (LTE)
› RX sensitivity @ ARP – 128,9dBm (WCDMA, 3GPP, w ASC) 4 carriers 20MHz IBW EDGE Evolution ready HSPA Evolution ready Built in ASC/TMA support Built in VSWR
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› › › › › ›
RUS
RUS
Multistandard, single mode RUS config
RUS
Multistandard, mixed mode RUS config
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Figure 4-25: Multistandard Radio Unit (RUS)
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GSM BSS Integration for Field Maintenance
RBS 6000 Transport Options
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The RBS 6000 is provided with extra space that can be equipped with a wide range of alternative transport solutions by means of Ericsson.s RAN-Transport portfolio, e.g. Site Integration Unit, MINI-LINK and Marconi OMS. These products are part of Ericsson IP RAN solution.
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Figure 4-26: RBS 6000 Transport Options
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Ericsson RBS Overview
Remote OMT over IP
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The Remote OMT over IP (ROMT/IP) has the same functionality as the locally connected OMT. The difference is that it can be remotely connected over TCP/IP to any RBS via BSCs that are connected to a TCP/ IP network. However, if connected to an APG, FSecure Client SW must also be installed into the PC host. The signalling between the BSC and the RBS is embedded in the LAPDsignalling where the signalling for ROMT/IP and the signalling for OML share the CF-link. Compared with Remote OMT, it is not necessary to allocate a whole PCM timeslot.
TCP/IP ROMT/IP
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RBS 2000
The Remote OMT Over IP (ROMT/IP) has the same functionality as the locally connected OMT. The difference is that it can be remotely connected over TCP/IP to any RBS via BSCs that are connected to a TCP/ IP network.
Figure 4-27: Remote OMT over IP
Some of its capabilities are listed bellow:
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› Getting detailed information about an RBS 2000 - The information can be used to remotely verify that an RBS 2000 is correctly configured and to perform preventive maintenance
› Fault localization of an RBS 2000 - Experts can use the ROMT/IP to perform fault localization and to guide service personnel at site › Restart of a whole RBS 2000 or a part of an RBS 2000 - The same type of restart that is achieved by pushing a reset button in an RBS 2000 can be performed with the ROMT/IP. This may be useful in situations with abnormal RBS behavior
Figure 4-28: Remote OMT over IP Main used for...
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Technical Descriptions
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12.1.1.1
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The Remote OMT over IP (ROMT/IP) is installed on a PC. ROMT/IP and BSC communicates over TCP/IP. The signalling between the BSC and the RBS is embedded in the LAPD signalling. A STOC or APG is required in the BSC. If ROMT/IP is connected via APG, an FSecure SSH Client also has to be installed on the ROMT/IP PC. One OMT user (via locally connected OMT, Remote OMT or ROMT/IP) at the time can be connected to one RBS. Each BSC can simultaneously handle maximum four (4) ROMT/IP users. From the BSC it is possible to activate and deactivate the ROMT/IP functionality.
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The ROMT/IP connection to RBS is initiated by the ROMT/IP while the BSC is responsible to setup the connection towards the RBS. When the connection is established, messages will be sent transparently through the BSC between the ROMT/IP and the RBS. The communication link will be supervised by the BSC by sending heartbeat messages to both the ROMT/IP and the RBS. All messages between the BSC and the RBS will be sent embedded in LAPD over the PCS-X layer.
› Optional feature activated on the BSC › The RMOT/IP user via STOC is required to make authenticated connection (CONNID) to the RBS › Each BSC can handle simultaneously 4 ROMT/IP users
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› The BSC is responsible to set up the connection towards the RBSs
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Figure 4-29: Remote OMT over IP
12.1.1.2
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Prerequisites using STOC access 1. The BSC must be equipped with a Signalling Terminal for Open Communications (STOC) to connect TCP/IP. RPG-2E and RPG3 are supported. If the BSC is equipped with a BSC LAN Switch for IP connectivity then the IP connection to the ROMT/IP is connected to the switch. The STOC is in this case also connected to the BSC LAN Switch. 2. The LAPD configuration shall follow the recommendations in the handbook for dimensioning of the LAPD.
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Ericsson RBS Overview
4. The ROMT/IP functionality has to be activated according the OPI.
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3. This is an optional feature. The feature must be activated and configured in the BSC.
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5. The ROMT/IP user must have the knowledge of the following parameters to be able to make a connection to the RBS: The Port number and IP-address to the BSC/STOC towards the RBS (as given in BSC RXOCI command).
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The RBS Address (MO-Identity)
The dedicated Password for this feature and for this specific session.
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› The ROMT/IP user must have the knowledge of the following parameters to be able to make a connection to the RBS: – The Port number and IP-address to the BSC/STOC towards the RBS (as given in BSC RXOCI command) – The RBS Address (MO-Identity) – The dedicated Password for this feature and for this specific session
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Figure 4-30: Remote OMT over IP
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Command Handling
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Objectives
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5 Command Handling
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Apply the command structure used in RBS/BSC communication, using the WinFIOL software and command documentation: › Define the purpose of Man-Machine Language (MML) commands › List varius command parameters › Interpret the format of commands › Use ALEX to search for a given command › Differentiate between CODs, PODs, and OPIs › Explain the difference between “RL” and “RX” commands › Given a list of commands, match a commond with its function
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Figure 5-1: Objectives
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GSM BSS Integration for Field Maintenance
MML Command Handling
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The purpose of this chapter is to give an overview of command structure used in communicating with the RBS through the BSC.
Command lines are entered into a tool called WinFIOL (usually located at the BSC).
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› Designed to help technicians “talk” to the RBS via the BSC e.g., for cell or RBS defining, troubleshooting, monitoring, etc. › Command lines are entered via WinFIOL › Each MML command has five letters › A description of each command can be found in ALEX › Some examples of commands are: › rxmsp › rxmfp › rlcrp › rlstp
Figure 5-2: Man-Machine Language (MML)
1.1 1.1.1
Anatomy of an MML Command
Command String
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Some parameters have values (use an = sign)…
Command String
… other parameters do not have values
rxmfp:mo=rxotg-99, faulty, subord; MML command
A colon (:) separates the MML command from the parameter field
Parameter field (not always used)
Commas (,) separate multiple parameters
All commands end with a semicolon (;) – regardless of whether parameters are used or not
Figure 5-3: Anatomy of an MML Command
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Command Handling
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As seen in Figure 5-3, MML command lines (strings) are made of essentially two parts – the command itself and the associated command parameters (some required, some optional). However, it is important to remember that not every MML command has associated parameters.
20
If a specific MML command does have associated parameters, the command and its parameter field are always separated by a colon (:). Furthermore, regardless of whether the command has associated parameters or not, the command line is always terminated with a semicolon (;).
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If a command has multiple parameters, the parameters are separated by a comma (,).
RBS Technician Commands
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Some parameters have associated values, where others do not. If the parameter has a value, the parameter and its value are separated by an equal sign (=).
The commands you will be using in this course (and on the job) are made up of five letters. Each command has a specific function.
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rxmfp
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There are only a few letters used at the end of MML commands. The more common ones are: p = Print c = Change i = Initiate e = End
If a command begins with: rx - it has to do with Managed Objects (MO)
rl - it has to do with cells
NOTE: it’s good practice to type command lines in WinFIOL in lower case. That way, numbers are easily distinguished from letters, and check printouts are easily distinguished from command input. Figure 5-4: Additional Command Information
Note in Figure 5-4 that the last letter of the command is especially significant:
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17
20
Print (p) – If a command ending in “P” is executed, it will simply produce a WinFIOL on-screen display (or “printout”) of the current system status. Change (c) – Commands ending in “C” indicate that system parameters previously established need to be modified. Initiate (i) – Commands ending in “I” indicate that system parameters will be defined. End (e) – Commands ending in “E” indicate that system parameters will be deleted or halted.
M
The MML commands you will use in this course will most likely begin with the letters “RL” or “RX”. These mean the following:
RX – The command is related to MO functionality
O
RL – The command is related to cell functionality
TE LE C
1.2
Using Alex to Research Commands
So how do you know which commands have parameters, which do not, etc.? Additionally, how do you know which commands to use? Ericsson employs a tool called the Active Library Explorer (ALEX) to store information on MML commands.
1.2.1
Command Descriptions (CODs)
ET H
IO
A Command Descriptions (COD) gives important information about a particular command. This information includes command format (which parameters, if any, are used, etc.), a description of each parameter (listed alphabetically), a description of the function behind a command, examples of a command’s syntax, WinFIOL printouts (if any) displayed as a result of executing the command, and a glossary of abbreviations used in the COD.
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Command Handling
17
RXMFP:RADIO X-CEIVER ADMINISTRATION MANAGED OBJECT FAULT INFORMATION, PRINT Format / \ |MOTY=moty[,FAULTY] | RXMFP:+ +; |MO=mo...[,FAULTY][,SUBORD]| \ / 1.2 Parameters FAULTY Faulty This parameter specifies that only information on faulty managed object...
20
1
2 Function This command initiates printing of fault information for one or more managed object instances or all ...
M
3 Examples RXMFP:MOTY=RXOTF,FAULTY; The fault information, is printed for all faulty TFs in...
O
4 Printouts (Fault codes etc.) 4.3 Answer Printouts RADIO X-CEIVER ADMINISTRATION MANAGED OBJECT FAULT INFORMATION
1.2.2
TE LE C
Figure 5-5: Typical Command Description (COD)
Printout Descriptions (PODs)
A Printout Description (POD) describes, in detail, WinFIOL on-screen printouts, including the format (headings, etc.), parameters that make up the printout, and the function of the printout. CELL CONFIGURATION DTX DOWNLINK DATA
IO
1 Format 1.1 Printout CELL CONFIGURATION DTX DOWNLINK DATA CELL DTXD cell dtxd ... ...
ET H
1.2 cell dtxd
LZT1380709 R2A
Parameters Cell designation Discontinues downlink transmission. ON Discontinues downlink...
2 Function The answer printout is obtained in answer to the command RLCXP. The printout contains information about the status of DTXD specified by the command RLCXC. Figure 5-6: Typical Printout Description (POD)
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1.2.3
17
GSM BSS Integration for Field Maintenance
Operational Instructions (OPIs)
20
An Operational Instruction (OPI) is the Ericsson formalized description of how to perform certain system tasks. The OPI tells the user, step by step, how to perform the task. The OPI usually includes a set of commands. The instructions may relate to manual actions or regular command-line interactions with the system. Radio X-ceiver Administration, Managed Object for BTS Logical Model G12, Connect
M
1 Introduction 1.1 Scope This Operational Instruction describes the procedure to connect Managed Objects (MO) in the Base Transceiver Station (BTS). . .
TE LE C
O
2 Procedure 2.1 Prerequisites 2.1.1 Conditions 2.1.2 Data 2.1.3 Special Aids 2.2 Actions Base Station Hardware 1. Is the Base Station Hardware installed and in Remote Mode? Yes Go to Step 2. No Go to Step 39. Note: See the work order. 3 Additional Information 4 Glossary 5 References
Figure 5-7: Typical Operational Instruction (OPI)
1.3
Helpful Print Commands
IO
For RBS technicians, the following commands can be helpful in determining system status, including faults. There are several others that we will discuss, apart from these examles:
ET H
rxmsp - Find the operational status for all Managed Objects (MOs) in your jurisdiction (requires a script)
rxmfp - Find any faulty MOs in your jurisdiction (can be done with single command)
rlcrp - Show the radio resources (active traffic channels) of all cells (single command)
rxapp - Show the status of A-bis paths to all Transceiver Groups (TGs) in your jurisdiction Figure 5-8: Daily Commands to Run
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Cell-Related Concepts
O
Objectives
M
20
6 Cell-Related Concepts
TE LE C
Discuss cell-related concepts, obtaining cell definition, neighbor cell set-up, measurement reports, locating, and handovers entering commands and parameters, in practical exercises: › Express a high-level description of the cell/site integration process › Identify cell-related parameters and data › Create the necessary command file to define a cell
ET H
IO
Figure 6-1: Objectives
LZT1380709 R2A
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1
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Introduction
20
The purpose of this chapter is to give an overview of cell-related concepts. These include cell definition, commands, parameters, neighbor cell set-up, measurement reports, locating, and handovers.
M
Cell definition – setting up a cell and its necessary parameters – is the first step in the Cell/Site Integration process (Figure 6-2).
TE LE C
O
Cell
BSC
Order of work: › › › › › ›
BTS Site
Define Cell in MSC and BSC Define Base Station Hardware (Site) Connect Link to BSC Bring site into service and deblock Connect cell to site Activate cell
Figure 6-2: Cell/Site Integration Process
ET H
IO
A cell is an area where an MS makes a radio connection to the GSM network. More specifically, the MS receives a signal strength that is high enough to set up a connection on a dedicated channel, meaning the SDCCH or TCH, and maintain it. A cell is not the same as a “site”. A site is the BTS equipment that services the cell.
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Cell-Related Concepts
17
Distinction between:
› “Cell” – An area where a mobile station makes a radio connection to the GSM network
20
Cell X
› “Site” – Equipment (e.g. BTS and antennas) that services the cell
Cell Z
Cell Y
M
Site
ET H
IO
TE LE C
Figure 6-3: Cell/Site Distinction
O
› “3-Sector Site” – A BTS that services three cells
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2
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Hardware View of the GSM Network
20
In Chapter 2, we reviewed the following figure that details the hardware view of a typical GSM network: MSC Service Area 2
MSC Service Area 1
BSC 1C
M
BSC 2C
BSC 2B
O
BSC 1B
TE LE C
BSC 2A
PSTN
TRC/BSC 1A
TRC 2A
MSC/VLR 1
MSC/VLR 2
AUC GMSC
HLR EIR
MSC Boundary BSC Boundary PCM Links Base Station (RBS)
ET H
IO
Figure 6-4: Hardware View of a Network
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2.1
17
Cell-Related Concepts
LAI and CGI
Location Area Identity (LAI) 3 digits
2 or 3 digits
16 bits
20
Location Area Identity (LAI) and Cell Global Identity (CGI) are cell-related parameters that make up the software side of the GSM network.
MNC
LAC
Mobile Network Code
Location Area Code
M
MCC Mobile Country Code
3 digits
O
Cell Global Identity (CGI) 2 or 3 digits MNC
Mobile Network Code
16 bits
LAC
CI
Location Area Code
Cell Identity
TE LE C
MCC
Mobile Country Code
16 bits
Location Area Identity
› Paging done by Location Area (LA) › Mobiles contact Visitor Location Register (VLR) when entering new LA › CGI is unique for every cell in the world
Figure 6-5: LAI and CGI Parameters
IO
It is important for the cellular network to know the location of a mobile, since paging signals are distributed in one Location Area (LA) only. A record in the MSC/VLR administers a mobile location by means of the LAI. When the MS moves from one LA to another, it sends a location-updating request to the MSC/VLR. The LAI parameter is made up of three numbers (expressed as MCC-MNC-LAC):
ET H
LZT1380709 R2A
MCC – Mobile Country Code (3 digits). This number is fixed for every country, so it cannot deviate within a country’s borders. MNC – Mobile Network Code (2 or 3 digits). This number refers to the network operator and is fixed per operator. It cannot deviate within an operator’s jurisdiction. LAC – Location Area Code (a number between 1 and 65535). This number is set by the network operator. Every cell belongs to exactly one LA, and LAs are unique to operators’ individual networks.
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17
As you can see from Figure 6-6, the CGI parameter is directly based on the LAI parameter and is a unique identifier for every GSM cell in the world. CGI is made up of four digits:
MCC
MNC
LAC
CI – Cell Identity (a number between 0 and 65535). The CI must be unique to the LA.
M
20
MSC Service Area 2
TE LE C
MSC Service Area 1
O
LAI and CGI are the two main parameters that make up the software view of the network.
Location Area Identity LAI = 310-550-11
Location Area Identity LAI = 310-550-21
Location Area Identity LAI = 310-550-22
Location Area Identity LAI = MCC + MNC + LAC
Location Area Identity LAI = 310-550-12
Cell Global Identity (= LAI + CI) CGI = 310-550-21-66
Location Area Identity LAI = 310550-23
Location Area Identity LAI = 310-550-24
MSC Boundary
IO
Location Area Boundary Cell Boundary
CGI is the Cell Global Identity, a unique identifier for an individual cell, consisting of MCC-MNC-LAC-CI
ET H
Figure 6-6: Software View of a Network
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HW Network
SW Network MSC
MSC TRC/BSC
BTS BTS BTS
MSC TRC/BSC
LA
MSC
Cell Cell Cell
O
LA
BTS BTS BTS
TE LE C
BSC
Cell Cell Cell
20
BTS BTS BTS
M
BSC
LA
17
Cell-Related Concepts
BTS BTS BTS
LA
Cell Cell Cell Cell Cell Cell
ET H
IO
Figure 6-7: Hardware vs. Software Hierarchies
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Cell Definition and Configuration
3.1
MSC Cell Definition
20
3
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GSM BSS Integration for Field Maintenance
TE LE C
O
Cell
M
A cell must be defined in the MSC as well as in the BSC. This is so that interBSC and inter-MSC handovers can be handled. The following single command line is used for MSC cell definition:
A cell must be defined in the MSC as well as in the BSC. This is so that inter-BSC and inter-MSC handovers can be handled. The following command is used:
mgcei:cell=cell, bsc=bsc, cgi=cgi;
It should be noted that the BSC might have two digits for its LAI (e.g., 01), and the MSC may have three digits (e.g., 010), or vice versa.
Figure 6-8: Defining a Cell in the MSC
IO
Notice that the command includes the CGI parameter. It should also be noted that the BSC might have two digits for its LAI (e.g., 01), and the MSC may have three digits (e.g., 010), or vice versa.
ET H
3.2
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BSC Cell Definition and Configuration
A cell is defined and configured in the BSC using the following commands. Please note that not all the commands to define a cell are listed here, but these are the main commands you will be using in this course.
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Cell-Related Concepts
Cell X
› › › ›
Site
Cell Y
M
Cell Z
O
The following slides detail the various parameters for the commands above.
20
Transmission (DTX) on the downlink RLCPC – Configures power data RLCFI – Configures frequency data RLLOC – Configures locating data RLSSC – Configures cell system information data sent on the SACCH and BCCH › RLMFC – Configures measurement frequencies › RLNRI – Defines neighbor cells › RLSTC – Changes the cell state
17
› RLDEI – Defines the cell › RLDEC – Describes data › RLCXC – Configures Discontinuous
Figure 6-9: Commands to Define Cells in the BSC
TE LE C
IO
ET H
LZT1380709 R2A
RLDEI: Radio Control Cell, Definition of Cell, Initiate – Command used to define a cell RLDEC: Radio Control Cell, Description Data, Change – Command used to describe data for the cell RLCXC: Radio Control Cell, DTX Downlink, Change – Configures Discontinuous Transmission (DTX) on the downlink for the cell RLCPC: Radio Control Cell, Configuration Power Data, Change – Configures power data for the cell RLCFI: Radio Control Cell, Configuration Frequency Data, Initiate – Configures frequency data for the cell RLLOC: Radio Control Cell, Locating Data, Change – Configures locating data for the cell RLSSC: Radio Control Cell, System Information SACCH and BCCH Data – Configures cell system information data sent on the SACCH and BCCH RLMFC: Radio Control Cell, Measurement Frequencies, Change – Configures measurement frequencies for the cell RLNRI: Radio Control Cell, Neighbor Relation, Initiate – Defines neighbor cells of the cell you are defining/configuring RLSTC: Radio Control Cell, Cell State, Change – Changes the cell state
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GSM BSS Integration for Field Maintenance
Internal and External Cells
20
3.2.1
17
We will be discussing the various parameters that make up these commands’ parameters – in addition to some new R10 features – throughout the remainder of this chapter.
M
A cell can be defined in the BSC as internal or external. Internal cells are fully controlled by their own BSC, whereas external cells are not controlled by their own BSC. However, certain data must be known to carry out a handover from cells in their own BSC to cells controlled by another BSC.
TE LE C
O
Outer cells are controlled not only by another BSC but also by another MSC. Outer cells that border the BSC in question must be defined to prevent unnecessary inter-MSC handovers
It is required to define some cells though they are outside the BSC. This is done by including the ext parameter in the definition command:
rldei:cell=cell,ext;
MSC Boundary BSC Boundary Location Area Boundary
Internal Cells External Cells Outer Cells
IO
Figure 6-10: Internal, External, and Outer Cells
The following command line is used to define a cell as internal or external:
ET H
RLDEI: CELL=cell, CSYSTYPE=csystype, EXT;
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Command parameters:
CELL – Cell designation or cell name constitutes a maximum of seven characters. It is recommended that the name of the site plus one more character, 1, 2, 3, or A, B, C, be used to identify the cell within the site; alternatively, identifying the aerial direction of the cell in a sector-site can be used for better cell identification.
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Cell-Related Concepts
Cell Description Data
M
3.2.2
17
CSYSTYPE – If the BSC global system type is mixed, CSYSTYPE must be used to define to which system the cell belongs, GSM 800, 900, 1800, or 1900. EXT – Stands for “external cell”, meaning that the cell belongs to another BSC. Note: The global system type for the BSC is defined using the command RLTYI. This command must be given before the first cell is defined.
20
O
Once the cell is defined (RLDEI), the RLDEC command is used to describe additional parameters of the cell.
TE LE C
RLDEC: CELL=cell, CGI=cgi, BSIC=bsic, BCCHNO=bcchno, BCCHTYPE= bcchtype, …
Cell is the cell name
CGI = 310-010-12-1231 cell= xyz123a Cell X
rsiteSite = xyz123
CGI = 310-010-12-1233 CGI = 310-010-12-1232 cell= Z xyz123c cell= xyz123b Cell
Cell Y
CGI is Cell Global Identity, a unique identifier for an individual cell, consisting of: MCC-MNC-LAC-CI
ET H
IO
Figure 6-11: Cell and CGI Parameters
LZT1380709 R2A
We have already discussed the parameters Cell and CGI. In Chapter 3, we noted that the BSIC was transmitted over the Synchronization Channel (SCH). The BSIC parameter is made up of the National Color Code (NCC) and Base Station Color Code (BCC) values.
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GSM BSS Integration for Field Maintenance
310 - 123 - 456 - 789
17
CGI = MCC (Mobile Country Code) Fixed for every country; cannot deviate
O
CI (Cell Identity) Set by operator in BSC; CI must be unique to LA
M
LAC (Location Area Code) Set by operator in MSC. Every cell belongs to exactly one LA. LAs are unique for operator’s network
20
MNC (Mobile Network Code) Fixed (and different ) for every operator; cannot deviate
Figure 6-12: Additional Notes about the CGI Parameter
TE LE C
Each operator in a country is assigned one NCC value to ensure that the same NCC is not used in adjacent Public Land Mobile Networks (PLMNs). The purpose of the BSIC is to distinguish between cells that come from different clusters but have the same carrier frequency. In addition, it can be used to distinguish between cells from different operators on the border between two countries. It is essential for the locating algorithm that the correct neighboring cells are evaluated.
IO
Cells that are close to country borders are given different NCC values. In this case, the MS does not perform a call set-up in another country or a different PLMN, which means that the operator has saved signaling and the subscriber has saved money. This method can also be used inside a country to prevent signaling and handovers between different MSCs. If a call setup in another country or a different PLMN is permitted, the parameter NCCPERM (which will be discussed later in this chapter) supersedes NCC.
ET H
BCC is used as protection against co-channel interference. For this purpose, BCC must be allocated as wisely as possible. It is recommended that all cells in a given cluster use the same BCC. In doing so the range of a certain BCC is maximized.
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Cell-Related Concepts
17
Cell in same N/W with same ARFCN
Cell in another N/W with same ARFCN BSIC=41 C0=600
BSIC A two-digit number for each cell made up of the NCC and BCC.
20
BSIC=32 C0=600
BSIC=43 C0=600
Handover Candidate
O
Network Boundary
NCCPERM (NCC Permitted) Defines the allowed NCCs on the BCCH carriers for which the MS is permitted to report measurements.
M
3 && =0 rk 7 o erm tw 4&& cp s ne = c n t hi ork erm etw in p c n nc t hi s in
TE LE C
Figure 6-13: BSIC and NCCPERM Parameters
The BCCHNO (BCCH number) parameter is the ARFCN for BCCH. Valid values are 1 through 124 (GSM 900), 128 through 251 (GSM 800), 512 through 885 (GSM 1800), and 512 through 810 (GSM 1900). Remember (from Chapter 3) that the BCHs and CCCHs are transmitted over the BCCH. marks the timeslot where the BCHs and CCCHs are transmitted. C0 = BCCH carrier C1 = TCH carrier C2 = TCH carrier C3 = TCH carrier
512
C0
524
C1
Cell Z
IO
ET H LZT1380709 R2A
Cell X
520
Cell Y C0
516
C0
BCCHNO is the ARFCN used for C0 (the BCCH carrier)
Figure 6-14: BCCHNO Parameter
The BCCHTYPE parameter indicates the combinations of wanted logical channels on the frequency and timeslot defined for the BCCH in the cell (COMB, COMBC or NCOMB). This concept was discussed in the Chapter 3.
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3.2.3
20
17
The RLDEC command involves other parameters (NEWNAME, AGBLK, MFRMS, etc.), but you can read about these in ALEX during the Cell Definition exercise. Note that these additional parameters will not be necessary for the command in that exercise.
Cell Configuration Frequency Data
M
If more frequencies than the BCCH ARFCN must be added to the cell, for instance, traffic channel ARFCNs (DCHNO), these frequencies are defined separately using the following command line: RLCFI: CELL=cell, CHGR=chgr, DCHNO=dchno;
O
If subcells exist, new frequencies are added to the Channel Group (CHGR). Cell X
512
C0
524
C1
TE LE C
C0 = BCCH carrier C1 = TCH carrier C2 = TCH carrier C3 = TCH carrier
In the example at right, DCHNO = 524
Cell Z
520
Cell Y C0
516
C0
DCHNO is the ARFCN(s) used for TCH carrier(s)
IO
Figure 6-15: DCHNO Parameter
ET H
3.2.4
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Discontinuous Transmission (DTX) If nothing is said into an MS microphone, there is no point sending anything at all in the air. When the Discontinuous Transmission (DTX) feature is used, the system only transmits when speech is detected over the connection. This decreases the power consumption in the MS and in the BTS, and reduces the amount of energy emitted into the air.
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Cell-Related Concepts
20
17
During a normal conversation, the participants alternate so that each is silent for about 50% of the time. If the transmitter is silent while there is nothing to be sent, the power consumption in the mobile station is decreased as well as the amount of emitted radio power. Less radio power generates less interference. Since the power level used when transmitting is unaffected, the C/I will be raised for all connections when using DTX. › When there is no speech, the TX stops transmitting › However, SACCH messages are always sent
yakyak-yakyak-yakyak-yakyak-yakyak-yak
SACCH bursts
TE LE C
O
TX Bursts
M
yakyak-yakyak-yakyak-yakyak-yak
DTXU controls Discontinuous Transmission on the uplink
Speech Activity = on = off
DTXD turns Discontinuous Transmission on the downlink on or off
Figure 6-16: Discontinuous Transmission (DTX)
DTX is implemented via two commands – RLCXC and RLSSC. In the RLCXC command line, the parameter DTXD (values ON or OFF) implements DTX for the downlink. In the RLSSC command line, the parameter DTXU (values 0, 1, or 2) implements DTX for the uplink.
Power Data Configuration
IO
3.2.5
The RLCPC command is used to configure cell power data:
ET H
RLCPC: CELL=cell, MSTXPWR=mstxpwr, BSPWRB=bspwrb, BSPWRT=bspwrt;
LZT1380709 R2A
Command parameters:
MSTXPWR – Maximum transmit power (in dBm) for an MS on a connection; most outdoor macro sites will have this set to 30 dBm (1 watt), whereas indoor sites will have lower settings to prevent the RX from being saturated.
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GSM BSS Integration for Field Maintenance
M
MSTXPWR is the maximum permitted transmit power (in dBm) for an MS
TE LE C
O
Most outdoor macro sites will have this set to 30 dBm (1 watt). Indoor sites will have lower settings to prevent the RX from being saturated. Figure 6-17: MSTXPWR Parameter
BSPWRB – BTS nominal output power (in dBm) for the RF channel number which has the BCCH. BSPWRT – BTS nominal output power (in dBm) for the RF channels which do not have the BCCH.
ET H
IO
The indicated power is the nominal power of the transmitter in the BTS, not the Effective Radiated Power (ERP). If a subcell structure exists, the parameters MSTXPWR and BSPWRT must be specified for each subcell. If the cell is external, only parameter MSTXPWR is valid.
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BSPWRB is the TX power for BCCH carrier BSPWRT is the TX power for TCH carrier
BSPWR is the ERP for BCCH carrier BSTXPWR is the ERP for TCH carrier
20
T R U
Note that the reference point for BSPWR & BSTXPWR can be here
TMA
C D U
M
B T S
A N T
17
Cell-Related Concepts
BSPWR is calculated ERP for BCCH carrier
BSPWRT is the TX power for TCH carriers or overlaid subcells
BSTXPWR is calculated ERP for TCH carriers
O
BSPWRB is the TX power for BCCH carrier or underlaid subcells
3.2.6
TE LE C
Figure 6-18: Base Station Power Parameters
Cell System Information Data Sent on SACCH and BCCH System information sent on the SACCH and BCCH is configured using the RLSSC command: RLSSC: CELL=cell, ACCMIN=accmin, CCHPWR=cchpwr, DTXU=dtxu, NCCPERM=nccperm,… Two parameters in particular are ACCMIN and CCHPWR:
IO
ET H
LZT1380709 R2A
ACCMIN – Stands for “Access minimum signal level” and defines the minimum received signal level (in dBm) at the MS for permission to access the system (Figure 6-19). CCHPWR – Stands for “Control channel power” and defines the maximum Transceiver Power Level (TXPWR), in dBm, an MS may use when accessing on a Control Channel (Figure 620).
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GSM BSS Integration for Field Maintenance
MS further away from BTS Detected SS = -105 dBm Access not allowed
17
ACCMIN = 100 ( i.e., -100 dBm)
20
Detected SS = -75 dBm Access allowed
M
ACCMIN is the minimum RX signal level in (neg) dBm at the MS for permission to access the system.
RACH: TXPWR = 30
CCHPWR = 43
TE LE C
CCHPWR = 30
O
Figure 6-19: ACCMIN Parameter
RACH: TXPWR = 29
GSM800 : Ms class 5 P=29 dBm
CCHPWR is Control Channel Power. Maximum transmitter power level (TXPWR) in dBm an MS may use when accessing on a control channel (CCH).
Figure 6-20: CCHPWR Parameter
3.2.7
Measurement Frequencies
ET H
IO
For handover possibilities, MSs must measure the signal strength (SS) of neighboring cells via their individual BCCH (C0). A list of BCCHs is called the BCCH Allocation List (BA List), collected by the BSC, and transmitted to the MS. The command used to initiate or add frequencies that the MS will measure on in the cell is RLMFC:
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RLMFC: CELL=cell, MBCCHNO=mbcchno [,LISTTYPE=listtype] [,MRNIC];
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Cell-Related Concepts
Measure Neighbors
Measure Neighbors
20
17
Listen to PCH
Measure Neighbors
Measure Neighbors
Question: How does the MS know which ARFCNs to listen to? ?
? ?
?
O
?
?
M
?
?
TE LE C
?
Figure 6-21: Measuring Neighbors
Command parameters:
ET H
IO
LZT1380709 R2A
MBCCHNO – The ARFCN for measurement on the BCCH; in dual-mode systems, frequencies from both systems can be used simultaneously. LISTTYPE – Optional parameter indicates if the BA List of measurement frequencies is to be used by the MS for measurements in idle mode or for measurements in active mode. If the parameter is not used, both idle and active mode measurements will be taken. MRNIC – Optional parameter; if used, the change of frequencies is executed immediately. As a consequence, the MS delivers incorrect measurements until it has read the complete list from system information. The BSC takes this into account when evaluating the measurement reports (MRs). If MRNIC is excluded, the list is updated as soon as there is a suitable point of time.
Up to 32 measurement frequencies can be defined in one cell. The indicated MBCCHNO must correspond to the BCCH-carriers of the cells, indicated in the neighbor relationship.
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C0 = 533
C0 = 519 C0 = 530
C0 = 543
C0 = 523 C0 = 540
C0 = 515 C0 = 522
20
C0 = 512
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GSM BSS Integration for Field Maintenance
M
Answer: The ARFCNs for C0 of all defined neighbors is sent on the BCCH in the cell. This list is called BCCH Allocation (BA) List. There are two separate BA Lists – one is for idle mode and one is for active mode.
O
MBCCHNO is the ARFCN for measurement on the BCCH.
TE LE C
LISTTYPE is the type of measurement frequency list. If this parameter is not used, it is assumed that the frequencies listed will be placed on both the idle and active list. Figure 6-22: Neighbor Cells: BA List
If a new cell is added to the network, the new cell must know the ARFCN of its own BCCH carrier (BCCHNO) as well as the BCCH ARFCNs of the neighboring cells. The neighboring cells must also know the BCCH ARFCN of the new cell.
3.2.8
Neighbor Cell Definition
It is mandatory to define neighbor relationships. These relationships control the handover between cells. The command to set up neighboring cells is RLNRI:
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RLNRI: CELL=cell, CELLR=cellr [,SINGLE]; Command parameters:
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CELLR – Related cell to the new cell being defined and configured; the relationship between the cells is mutual, meaning that handovers in both directions are permitted unless the SINGLE parameter is used. SINGLE – Optional parameter that defines the relationship between the new cell and the neighbor (external) cell as oneway. The handover from an internal to an external cell is initiated and controlled by the internal cell’s own BSC. The handover in the other direction – from the external to the internal cell – is handled by the external cell’s BSC.
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Cell = F C0 = 523
Cell = B C0 = 519 Cell = E C0 = 530 Cell = G C0 = 515
Cell = C C0 = 533 Cell = D C0 = 543
Cell = H C0 = 522
Cell = J C0 = 540
20
Cell = A C0 = 512
17
Cell-Related Concepts
M
To define a neighbor cell, use the rlnri command:
rlnri:cell=cell,cellr=cellr[,single];
TE LE C
Figure 6-23: Defining Neighbors
O
CELLR is the name of the neighbor cell. Reciprocal relation is automatically formed. SINGLE = Indicates only one-way handover from CELL to CELLR is allowed (has no values).
Up to 64 neighbors can be defined per cell. However, 32 mutual neighbors can be defined for a cell.
3.2.9
Measurement Reports (MRs)
Figure 6-24 explains the concept of measurement recording. Figure 6-25 explains the significance of RxLev (signal strength) and RxQual (Bit Error Rate, or BER) in MRs. Please fill in the blanks as the instructor presents these slides.
ET H
IO
RxLev is the name for signal strength measurements
If the SS is: Then RxLev is: less than -110 dBm 0 -110 dBm to -109 dBm 1 -109 dBm to -108 dBm 2 -108 dBm to -107 dBm 3 ... ... -49 dBm to -48 dBm 62 greater than -48 dBm 63
RxQual is the name for quality or Bit Error Rate (BER) measurements
If the BER is: RxQual is: and dtqu* is: less than 0.2% 0 0 0.2% to 0.4% 1 10 0.4% to 0.8% 2 20 0.8% to 1.6% 3 30 1.6% to 3.2% 4 40 3.2% to 6.4% 5 50 6.4% to 12.8% 6 60 more than 12.8% 7 70
*dtqu (Deci-Transformed Quality Units)
Figure 6-24: Statistics for Measurement Reports
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523
17
2
520
3 1
517 Measurement Report 515 SS RxLev RxQual Neighbor List 529 RxLev ARFCN BSIC 55 517 526 22 51 545 22 541 45 551 22 40 520 538 22 22 548 22 555 12 558 22 551
548
20
Active BA List 515 517 520 523 526 529 532 535 538 541 545 548 551 555 558 559 ...
535
532 545
559
558
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1 After the call is established, the BSC sends the Active BA List to the MS. This list contains
the ARFCNs for C0 for all defined neighbors and can be as long as 32 ARFCNs. 2 The MS measures the SS (RxLev) and BER (RxQual) of the Serving Cell AND It also
O
measures SS on all the neighbors on the BA List and makes a Neighbor List 3 The MS sends the Measurement Report to the BTS.
TE LE C
Figure 6-25: Measurement Reports: Active Mode
Measurements are taken at intervals. For every TCH frame, there are two TSs where the MS must receive a burst from the serving cell and transmit to the serving cell. This allows the MS to make measurements in the intervening timeslots and find the BSIC of neighboring cells. The last frame in a TCH multiframe is an idle frame. In this frame, the MS does not transmit to, nor receive from, the BTS. This allows the MS to collect BSICs from neighbor cells in order to provide complete information to the BSC. TCH Frame
Idle Frame
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DL
UL
ET H
Measurement Intervals
Idle Frame
› For every frame, there are two TSs where the MS must receive a burst from the serving cell and transmit to the serving cell. › This allows the MS to make measurements in the intervening time slots and find the BSIC of neighboring cells. › The last frame in a TCH multiframe is an Idle frame. In this frame, the MS does not transmit to, nor receive from, the BTS. This allows the MS to collect BSICs from Neighbor Cells to provide complete information to the BSC.
Figure 6-26: Measurement Intervals
There are two types of measurements – Full and Sub.
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Cell-Related Concepts
17
Full measurements are averages of SS and BER in every TCH frame. These averages are used to make up RxLev Full and RxQual Full measurements.
20
Sub measurements are averages of the SACCH bursts sent once every TCH Multiframe. The average of SS and BER in these SACCH frames is used to make RxLev Sub and RxQual Sub measurements. › Full Measurements are averages of the SS in every TCH frame
The average SS and BER in these frames is used to make RxLev Full and RxQual Full measurements
M
Any T T T T T T T T T T T T A T T T T T T T T T T T T TCH
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› Sub Measurements are averages of the SACCH bursts that are sent once every multiframe
I
A
A
The average SS and BER in these SACCH frames is used to make RxLev Sub and RxQual Sub measurements
A
TCH multiframe
Figure 6-27: Full and Sub Measurements
3.2.10
Locating
ET H
IO
A mobile telephony connection must be handed over between cells as the person using the phone moves around. There are several criteria that can be used for initiating this handover. The criteria serve different purposes, which, in turn, arise from a range of requirements that must be put on a mobile telephony system.
LZT1380709 R2A
The requirements are, broadly speaking, coverage, speech quality and capacity. Therefore, the purpose of the criteria is to provide a connection with sufficient signal strength (coverage and speech quality), to avoid disturbances (speech quality), to maximize the Carrier-to-Interferer (C/I) ratio (speech quality and capacity) and to even out the traffic load (capacity). The locating algorithm works out the basis for handover decisions and is implemented in the BSC. This is the algorithm for cell selection for active MSs (i.e., ongoing connections) after immediate assignment. The cell selection in the GSM network has two main objectives:
Quality and continuity of calls
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"Cell size" control in order to minimize total interference in the network
17
There are several Locating algorithms:
20
› Ericsson 1 Algorithm
› Ericsson 1 is complex, which means that it is difficult to optimize.
› Ericsson 3 Algorithm
O
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› Ericsson 3 is easier to handle (fewer parameters) and easier to understand than Ericsson1, but still possible to optimize.
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EVALTYPE is the type of Locating Algorithm evaluation used.
Figure 6-28: Locating (Handover)
There are two different basic algorithms to choose between: Ericsson 1 and Ericsson 3. They are selected by using the parameter EVALTYPE (in the RLLBC command) set to either 1 (for Ericsson 1) or 3 (for Ericsson 3). NOTE: Ericsson 2, which was a simpler algorithm but could not be optimized in some cases, was replaced by the Ericsson 3 algorithm in GSM R7. All cells must provide the following parameters for locating, no matter which algorithm you use:
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MSTXPWR (RLCPC command)
BSPWR (RLLOC)
BSTXPWR (RLLOC) – Base Station ERP
MSRXMIN (RLLOC) – Lower level of SS in MS
BSRXMIN (RLLOC) – Lower level of SS in BTS
However, each algorithm requires its own (additional) parameters. These will be listed under the explanation.
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3.2.10.1
17
Cell-Related Concepts
Ericsson 1
20
Ericsson 1 is based on the GSM specification. It is possible to use either pathloss, SS, or both for the handover decision. It is a complex algorithm involving many different parameters. Additional parameters (and their associated command) needed include:
MSRXSUFF (RLLOC) – Sufficient SS in MS
BSRXSUFF (RLLOC) – Sufficient SS in BTS
KHYST (RLNRC) – SS hysteresis (in dBm) when evaluating K-cells
LHYST (RLNRC) – SS hysteresis (in dBm) when evaluating L-cells
TRHYST (RLNRC) – SS hysteresis (in dBm) when transitioning between K- and L-cells
KOFFSETP or KOFFSETN (RLNRC) – SS positive (P) or negative (N) offset (in dBm) when evaluating K-cells
LOFFSETP or LOFFSETN (RLNRC) – SS positive (P) or negative (N) offset (in dBm) when evaluating L-cells
TROFFSETP or TROFFSETN (RLNRC) – SS positive (P) or negative (N) offset (in dBm) when transitioning between Kand L-cells
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M
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SS -59 dBm -65 dBm -69 dBm -75 dBm -85 dBm -95 dBm
20
RXMIN =90
Cell A B Accepted C Cells D E Cells Not Accepted F
17
M-criteria
M
MSRXMIN is a threshold for DL signal strength from neighboring cells, as measured by the MS, for allowing a cell to be eligible as a handover candidate. It is defined per cell.
O
BSRXMIN is the corresponding threshold for the UL signal strength to neighboring cells, as calculated from the DL measurements. It is defined per cell and given in relation to a reference point, e.g., as EiRP.
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Figure 6-29: Ericsson 1 Algorithm Step 1: M-criterion The serving cell can make measurements of the mobile’s signal for reporting to the BSC 3
1
2
3 dB 0) = 10 43 – (-6 = S
P PWR - IN,M L P = BS
PIN,MS= 1 -60 dBm The mobile can make downlink measurements to compare with MSRXMIN
BSTXPWR = BSPWR = 43 dBm
4
PIN,BTS= POUT,MS – LP = 30 – 103 = -73 dBm
Does the neighbor cell make uplink measurements of the mobile?
The BSC receives the Downlink SS of the neighboring cell from the MS in the Measurement Report, PIN,MS
The BSC ‘knows’ the output power of the neighboring cell from the parameters BSTXPWR and BSPWR 3 From these two, the BSC can calculate the Path Loss, LP, from BSPWR - PIN,MS
IO
2
4
Using the MS output power (also in the Measurement Report), the BSC can calculate PIN,BTS as POUT,MS - LP.
ET H
Figure 6-30: Neighbor Cell Uplink Measurements
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L Cells
SS -59 dBm -65 dBm -66 dBm -69 dBm -75 dBm -85 dBm -95 dBm
K-criteria
RXSUFF=70
20
RXMIN =90
Cell A B Svg C D E F
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Cell-Related Concepts
K Cells
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MSRXSUFF is the sufficient signal strength in negative dBm for path loss criteria in Mobile Station.
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BSRXSUFF is the sufficient signal strength in negative dBm for path loss criteria in Base Station.
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Figure 6-31: Ericsson 1 Algorithm Step 2: K-criterion
RXMIN =90
Cell A B Svg C D E F
SS -59 dBm -65 dBm -66 dBm -69 dBm -75 dBm -85 dBm -95 dBm
Cell A Srvg C B
L-criteria (Path Loss) SS RxLev Path Loss -59 dBm 51 BSTXPWR - RxLev -66 dBm 60 BSPWR - RxLev -69 dBm 41 BSTXPWR - RxLev -65 dBm 45 BSTXPWR - RxLev
RXSUFF=70
K Cells (by Rx SS)
IO
Figure 6-32: Ericsson 1 Algorithm Step 3: L-criterion
ET H
3.2.10.2
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Ericsson 3 Ericsson 3 was first implemented in GSM R7. It is based on the experience of achieving a better network performance by only considering SS at the handover decision. It is possible, by parameter settings, to achieve exactly the same evaluation in Ericsson 1 as in Ericsson 3. The main benefit with Ericsson 3 is less complexity, i.e. less parameters, and thereby an easier-maintained radio network. Additional parameters (and their associated command) include:
HYSTSEP (RLLOC) – SS separator
HIHYST (RLNRC) – SS hysteresis (in dBm) when evaluating high SS cells
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LOHYST (RLNRC) – SS hysteresis (in dBm) when evaluating low SS cells
OFFSETP or OFFSETN – SS positive (P) or negative (N) offset (in dBm) when evaluating cells with Ericsson 3 algorithm M-criteria
M
SS -59 dBm -65 dBm -69 dBm -75 dBm -85 dBm -95 dBm
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RXMIN =90
Cell A B Accepted Cells C D E Cells Not Accepted F
20
17
TE LE C
MSRXMIN is a threshold for DL signal strength from neighboring cells, as measured by the MS, for allowing a cell to be eligible as a handover candidate. It is defined per cell.
BSRXMIN is the corresponding threshold for the UL signal strength to neighboring cells, as calculated from the DL measurements. It is defined per cell and given in relation to a reference point, e.g., as EiRP.
Figure 6-33: Ericsson 3 Algorithm Step 1: M-criterion
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IO
RXMIN =90
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Cell A B Svg C D E F
SS -59 dBm -65 dBm -66 dBm -69 dBm -75 dBm -85 dBm -95 dBm
If Svg Cell > 70 then Svg Cell is high SS cell - use HIHYST
HYSTSEP=70
If Svg Cell < 70 then Svg Cell is low SS cell - use LOHYST
HYSTSEP gives the signal strength level specifying whether serving cell currently is a low or high signal strength cell; defined per cell LOHYST is the hysteresis used if the serving cell is a low signal strength cell. It is defined as a cell to cell relation; defined per cell
HIHYST is the hysteresis used if the serving cell is a high signal strength cell. It is defined as a cell to cell relation; defined per cell
Figure 6-34: Ericsson 3 Algorithm Step 2: Determination of Serving Cell Type
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Cell-Related Concepts
17
Ranking SS - HIHYST SS SS - HIHYST SS - HIHYST SS - HIHYST SS - HIHYST
20
SS -59 dBm -65 dBm -66 dBm -69 dBm -75 dBm -85 dBm -95 dBm
SS -59 dBm -66 dBm -65 dBm -69 dBm -75 dBm -85 dBm
M
RXMIN =90
Cell A B Svg C D E F
Cell A Svg B C D E
Qualifying neighbor cells are ranked by SS (with appropriate hysteresis and penalties)
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Figure 6-35: Ericsson 3 Algorithm Step 3: Ranking
TE LE C
All cells must provide the following parameters for locating: • MSTXPWR • BSPWR • BSTXPWR • MSRXMIN • BSRXMIN Ericsson 3 requires the following additional parameters: • HYSTSEP • HIHYST • LOHYST • OFFSETP or OFFSETN
IO
Ericsson 1 requires the following additional parameters: • MSRXSUFF • BSRXSUFF • KHYST • LHYST • TRHYST • KOFFSETP or KOFFSETN • LOFFSETP or LOFFSETN • TROFFSETP or TROFFSETN
Figure 6-36: Locating Parameters
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3.2.11
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Hysteresis
Since the handover algorithms are based on comparing the available handover candidates, the handover borders are fixed in space and independent of the direction in which the MS is moving. An adjustable safety margin against fluctuating SS – known as hysteresis – is added in this case. The main reasons for such fluctuations are fading, due to movements of the MS, or movements of objects in the surrounding area. A low hysteresis yields a sharp handover border, but a larger amount of fluctuating handovers.
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17
› As with cell reselection (in idle mode), handover does not occur at the border. › A signal strength hysteresis at the border is typically applied to prevent the “ping-pong” effect.
20
Hysteresis
Handover does not occur here at border
Cell X
M
Handover occurs here at border + hysteresis
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Figure 6-37: Hysteresis at Handover
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Cell Y
Hysteresis is reciprocal (by default) between cells, and this creates a “hysteresis corridor”. This corridor can be pushed towards one cell or the other using an offset. Hysteresis is reciprocal between cells, producing a hysteresis corridor... Cell Border
Hysteresis Corridor
Cell X
Hysteresis
Cell Y
The corridor can be “pushed” in one direction by using an offset…
IO
Hysteresis Corridor
Cell Y
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Cell X
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Offset
Figure 6-38: Reciprocal Hysteresis
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Cell-Related Concepts
Merry-Go-Round Effect
17
3.2.11.1
B-C
M
20
Consider three cells, A, B and C (Figure 6-39). An MS entering into the black (triangle) area will not be able to stay in a stable manner in any of the three cells. If the MS approaches the black area near Cell A, it will pass the C-A handover border and perform a handover to C. Once the MS is on C, the locating algorithm will notice that the MS is on the wrong side of the B-C handover border. Consequently, there will be a handover to B. Now, since the A-B handover border has been shifted with an offset, the MS will be on the wrong side of that handover border. A handover back to Cell A is then performed, and the merrygo-round is in motion.
Cell B
TE LE C
O
r rde bo
Offset A-B cell border
Original A-B cell border
Cell A
AC
bo rd er
Cell C
IO
Figure 6-39: “Merry-Go-Round” Effect
ET H
3.3
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Multi-Band Cell Feature
Since the GSM R10, the MULTI-Band Cell makes it possible to configure two different frequency bands in a cell with only one BCCH. The BCCH is configured on a frequency belonging to one of the frequency bands (BCCH frequency band), while the resources in the other frequency band (non-BCCH frequency band) provide more capacity to be used for traffic (Figure 6-40).
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17
Multi-Band Cell makes it possible to have dual-band RBSs, but with only one BCCH needed for both bands. Benefits:
20
RBS 1900
› Increased Capacity
Cell ACell and A B BCCH BCCH
– Since only one BCCH is necessary – Fewer cells to maintain
Cell B BCCH
RBS 800
M
› Easier O&M
– Fewer neighbor cells Figure 6-40: Multi-Band Cell
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› Improved Radio Network Quality
TE LE C
In order to be able to configure a Multi-Band cell, transceivers for different bands have to be synchronized by being located in the same RBS cabinet and/or by using the TG Synchronization option if the transceivers are located in different RBS cabinets.
ET H
IO
The channel allocation in a Multi-Band cell is performed with respect to the MS frequency capability. In order to be supported by a Multi-Band cell network, an MS has to be capable of listening to the BCCH, i.e. to support the BCCH frequency band. Multi-band MSs that support both frequency bands can be allocated any available resource within a cell. MSs that do not support the nonBCCH frequency band are always allocated resources from the BCCH frequency band.
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EDGE Evolution
4.1
EDGE Performance Today and Tomorrow
20
4
17
Cell-Related Concepts
Network Performance of Today
O
4.1.1
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Today’s EDGE technology offers greatly improved performance compared with standard GPRS and the first implementations of EDGE. The increased user bitrates and reduced latency offered by EDGE today enhance existing applications and make new services like music downloads, mobile TV and messaging services more attractive to users.
TE LE C
The performance of EDGE, as experienced by the end-user, is dependent on a variety of system characteristics. For example, a web download consists of multiple requests and downloads of objects and, consequently, the time it takes to download the page depends on the end-to-end round-trip time and user bit-rates in the system which are the main performance indicators for any packet data system. Performance is normally evaluated across a common set of subscriber applications. Today’s state-of-the-art EDGE networks typically offer user speeds of 200 kbit/s, and 250 kbit/s in peak, with end-to-end round-trip time (latency) of 150 ms . Features like advanced link quality control and persistent scheduling have improved performance significantly over standard GPRS and the first implementations of EDGE. For example, the time it takes to download a web page is about one-quarter that taken with standard GPRS.
Enhanced Applications Performance over EDGE
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IO
4.1.2
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EDGE enhances services provided by 2G systems with higher user bit rates and multi-media capabilities. EDGE is also an revolutionary path towards providing third generation services. The perceived end-user performance enabled by EDGE is good enough to make any service available today attractive. This includes e-mail, web browsing, music download and mobile TV.
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EDGE Evolution Performance Boost
17
4.1.3
M
20
To improve service performance in general, and facilitate conversational multimedia services, a number of enhancements to EDGE have been standardized in 3GPP. Known collectively as EDGE Evolution, these are included in Release 7 of the 3GPP standard. Peak bit-rates of up to 1 Mbit/s and typical bit-rates of 400 kbit/s can be expected. Round-trip times will be less than 100 ms and spectrum efficiency will be more than twice as good as today. EDGE Evolution can be gradually introduced as software upgrades, taking advantage of the installed base. With EDGE Evolution, end-users will be able to experience mobile Internet connections corresponding to a 500 kbit/s ADSL service.
O
EDGE Evolution will improve service performance and enable more efficient radio bearers. Different services may have different performance requirements in different areas, but EDGE Evolution is expected to improve the user-experienced performance across all services by:
Reducing latency to improve the user experience of interactive services and also to enhance support for conversational services such as multimedia telephony.
Increasing peak and mean bit-rates, to improve best-effort services such as web browsing or music downloads.
Improving spectrum efficiency, which will particularly benefit operators in urban areas where existing frequency spectrum is used to its maximum extent traffic volume can be increased without compromising service performance or degrading perceived user quality
Boosting service coverage, for example through interference reduction or more robust services. Increased terminal sensitivity improves coverage in the noise limited scenario.
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4.2
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EDGE Evolution – Dual Carrier Being part of EDGE Evolution, Dual Carrier Downlink, enable twice as high bitrate to the end-users compared to a single carrier allocation. Combined with 16/32QAM, peak bitrates of 1 Mbps to a single user is possible. This enable demanding mobile broadband and other high bitrate services in the GSM/EDGE network.
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Cell-Related Concepts
17
› Dual Carrier
M
20
– Enables downlink allocation of two carriers simultaneously to a single terminal – Timeslot allocation not changed, all timeslots can still be ondemand in order to not impact voice capacity – Any two carriers in the same band can be used, no impact on frequency planning or frequency hopping
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› Other benefits
– Increased trunking gain (better to let two users share 10 timeslots, than having 2 users with 5 timeslots each)
4.2.1
4.2.2
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Figure 6-41: EDGE Evolution – Dual Carrier Description
Benefits
Supported on all EDGE capable TRX leading to a fast and cost efficient roll out of wireless data services.
Up to 1000 kbps in downlink (with 32 QAM and 2x5 timeslots)
Operator Value
IO
Better utilization of existing network, i.e. higher throughput per kHz from existing HW. Cost-efficient SW only upgrades of network. Increased end user performance will increase mobile data usage.
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Possibility for new services
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Mobile Broadband
Higher quality mobile TV
Smart phones
New services will also have other positive effects:
Better operator image
Reduced churn
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Additional revenues
Flexible 3G rollout with Service continuity
Benefits for the Consumer
20
4.2.3
Dual antenna terminals will:
Improve coverage thanks to high bit rate at cell border and as well as generate fewer dropped calls.
M
Lower latency will:
Give faster response from applications
O
17
GSM BSS Integration for Field Maintenance
TE LE C
Dual carriers, higher modulation schemes (16QAM/32 QAM) and turbo codes in the downlink will:
Speed up Web Browsing, E-mail reading and file downloads.
Higher modulation scheme (16 QAM) in the uplink will: Speed up file uploads Increased Revenues
With twice as high bitrate delivered to the end-users it is possible to address new services and revenues within the GSM/EDGE network.
Technical Description
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4.2.4
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By allowing transmission on two GSM carriers simultaneously to the same user, it is possible to allocate more EDGE timeslots to this user. With Dual Carrier, 10 to 12 timeslots can be allocated to a single user, thus improving bitrates significantly compared to today’s terminals with 5-6 timeslots. Combined with 32QAM, the peak rate to a single user is 1 Mbit/s on a 10 timeslot allocation. If also Higher Symbol Rate is used, the bitrate is 1.2 Mbps. Dual Carrier can also be applied to today’s 8-PSK modulated EDGE, enabling approximately 600 kbps (10x59.2 kbps). Dual Carrier is only applicable in the downlink direction and only for EDGE connections.
© Ericsson AB 2012
LZT1380709 R2A
4.2.5
Commands and Printouts RLDDI: Radio Control Cell, Dual Carrier Downlink, Initiate
RLDDP: Radio Control Cell, Dual Carrier Downlink, Print
20
RLDDE: Radio Control Cell, Dual Carrier Downlink, End
17
Cell-Related Concepts
These new commands are used to activate (RLDDI), to deactivate
M
(RLDDE) and to print the values of activation status for EDGE Evolution Dual Carrier (RLDDP).
O
RLBDC: Radio Control Cell, Configuration BPC Data, Change
A new parameter ETCHTN is added to the existing command RLBDC.
ET H
IO
TE LE C
This parameter defines on which timeslot numbers the E-TCHs shall be configured in the channel group.
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IO
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Intentionally Blank
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20
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17
Managed Objects
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Objectives
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20
7 Managed Objects
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Define the Managed Object concepts and the RBS in a functional-oriented way, from the BSC point of view, and create command files defining MOs: › Define the Managed Object (MO) concept › Identity the logical model for RBS 2000 and 6000 › Explain the purpose of TEIS and DCPs › Create the necessary command file to define a TG and its related MOs
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IO
Figure 7-1: Objectives
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1
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Managed Object (MO) Concept
20
The hardware architecture in the RBS is not visible from the BSC, so a model of the RBS has been developed which is used both in the BSC and the RBS. This model is a logical representation of the hardware and software functionality of the RBS, describing the RBS in a functional-oriented way.
M
The model is presented as a set of Managed Objects (MOs). An MO does not necessarily have a one-to-one relation with a physical unit in the RBS. MOs can consist of hardware, software, or both.
O
There are two different types of logical models in the BTS – Logical Model G01 (which stands for “Generation 0”) represents the RBS 200 family, and Logical Model G12 (which stands for “Generation 1”) represents the RBS 2000 family.
TE LE C
NOTE: This course primarily deals with the integration of cell sites using RBS 2000 cabinets. Therefore, the RBS 200 series (along with Logical Model G01) will not be discussed.
Ericsson RBS 200
Ericsson RBS 2000
› Started late-1980s
› Started mid-1990s
› Uses Transceiver Group (TG) Model G01
› Uses Transceiver Group (TG) Model G12
IO
› RBS 200s were the first line of BTSs developed by Ericsson for GSM. They are still used by operators who bought them in the early years of GSM. › This course only deals with RBS 2000. Therefore, ignore anything related to “G01”.
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Figure 7-2: G01 vs. G12 Model
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2
17
Managed Objects
Logical Model G12
20
Since all types of base stations are not built up in the same way, different models use slightly different MO models. As stated previously, the MO model used in and towards RBS 2000 is Logical Model G12.
DP
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TF
CF
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RX
TRXC 0
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IS
TX TS 0 TS 7
(Up to 16 TRXCs)
TRXC 15
CON
8 Timeslots
RX TX TS 0 TS 7
8 Timeslots
Figure 7-3: Managed Object Model G12
In Figure 7-3, one MO is not shown. This model’s implementation of the BTS’s general functionality is called a Transceiver Group (TG).
ET H
IO
However, a TG can support a part of a cell, a whole cell, or up to 16 cells. One TG is normally synonymous with one BTS. However, in certain applications, more than one cell can be connected to the same TG, thus sharing functions in the TG.
LZT1380709 R2A
The MOs for RBS 2000 are divided into two major classes:
Service Objects (SO) handle functionality and are the owners of specific hardware units in the cabinet.
Application Objects (AO) handle functionality only and are under the administration of the SOs.
© Ericsson AB 2012
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SOCF Central Function
RXOCF-99
AOIS
AOTF
SOTRXC
Interface Switch
Timing Function
Transceiver Controller
Concentration
RXOIS-99
RXOTF-99
RXOTRX-99-0
RXOCON-99
AOTX
AORX
Transmitter
Receiver
RXOTX-99-0
RXORX-99-0
AODP Digital Path
RXODP-99-0
M
AOCON
20
Two classes of Managed Objects: › Service Objects (SO) › Application Objects (AO)
17
GSM BSS Integration for Field Maintenance
AOTS
O
Time Slot Handler
NOTE: “99” is an example TG number. This number can be from 0 to 512.
RXOTS-99-0-0
2.1.1
TE LE C
Figure 7-4: Managed Objects in RBS 2000
MCPA Application and MCTR
A BTS of the RBS 6000 product family can contain the new hardware unit RUS. Such BTSs contain Multi Carrier Power Amplifier (MCPA) based TRXs, where the digital part of each TRX is located on the DUG 20 unit, while the radio part is located in the RUS unit. The radio part includes the power amplifier and this will be capable of amplifying signals from many TXs at the same time, hence the name: Multi Carrier Power Amplifier (MCPA). A BTS using RBS 6000 with DUG 10 and RUG does not contain any MCPA based TRXs. One TRX can be connected to one MCPA only, for information on maximum number of TRXs per MCPA and number of MCPAs per RUS unit.
ET H
IO
It is possible to install and use MCPA based BTSs in networks run on BSS 07B (BSC 07B/OSS-RC 6.3) and later.
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LZT1380709 R2A
TE LE C
O
M
20
17
Managed Objects
Figure 7-5: MCPA
2.1.2
MO Classes for BTS Logical Model G12
The following MO classes exist for the BTS logical model G12:
Central Functions (CF).
Digital Path (DP)
LAPD Concentrator (CON)
Multi Carrier Transceiver (MCTR)
Receiver (RX)
ET H
IO
LZT1380709 R2A
Interface Switch (TS)
Time Slot
Timing Function (TF)
Transceiver Controller (TRXC)
Transceiver Group
Transmitter (TX)
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GSM BSS Integration for Field Maintenance
20
17
A TG MO consists of a maximum number of 16 TRXCs, a maximum number of 16 RXs, a maximum number of 16 TXs, a maximum number of 128 TSs, a maximum number of one CF, a maximum number of one IS, a maximum number of one TF, a maximum number of 16 MCTRs, a maximum number of one CON, and a maximum number of four DPs.
ET H
IO
TE LE C
O
M
A TG MO can be connected to a maximum number of 16 channel groups.
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Figure 7-6: RBS 6000 Logical Model G12
© Ericsson AB 2012
LZT1380709 R2A
MO Functionality
3.1
DXU-Related Functionality
20
3
17
Managed Objects
The following sections detail MOs that are directly related to DXU functionality.
3.1.1
Central Function (CF)
Interface Switch (IS)
O
3.1.2
M
The CF is the control part of a TG. It is a software function, handling common control functions within a TG. There is one CF defined per TG.
3.1.3
TE LE C
The IS provides a system interface to the PCM links and cross-connects individual timeslots to specific transceivers. There is one IS defined per TG.
Timing Function (TF)
The TF extracts synchronization information from the PCM links and generates a timing reference for the RBS. There is one TF defined per TG.
3.1.4
Concentration (CON)
IO
The CON (also known as the LAPD Concentrator) is used by the optional feature LAPD Concentration for RBS 2000. Therefore, the CON, as an MO, is itself optional. There is one CON defined per TG.
ET H
3.1.5
LZT1380709 R2A
Digital Path (DP) Digital Path Layer 1 reception and transmission are not part of the BTS logical model. However, each of the PCM systems terminating in the TG has an associated managed object known as the DP. Reports of transmission faults and supervision of transmission quality are carried over the A-bis O&M interface. That signaling is described using the DP. There can be up to four DPs defined per TG.
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3.2
17
GSM BSS Integration for Field Maintenance
TRU-Related Functionality
3.2.1
20
The following MOs are directly related to functions in the RBS’s transceivers (TRUs).
Transceiver Controller (TRXC)
3.2.2
O
M
The TRXC controls all the functions for signal processing, radio reception, and radio transmission. In a normal configuration, each TRXC (also known as TRX) corresponds to one TRU. There can be up to 16 TRXCs defined per TG.
Transmitter (TX) and Receiver (RX)
3.2.3
TE LE C
The MO representing the transmitter functions, for example, transmitted power and frequency in the bursts sent, is called the TX. The RX represents the radio receiving functions. There can be up to 16 TXs and RXs defined per TRXC.
Timeslots (TS)
ET H
IO
TS is the MO that represents the handling of timeslots. There can be up to eight TSs defined per TRXC.
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LZT1380709 R2A
Defining Managed Objects
4.1
Addressing of Managed Objects
20
4
17
Managed Objects
Figure 7-7 shows how the G12 Logical Model MOs are represented in various ways.
Definition Transceiver Group
CF
Central Function
IS
TF
n/a
BSC Command Parameter
CON DP
TRXC
Example
Value ranges for variables
RXOTG
RXOTG-x
x = 0 - 511
SOCF
RXOCF
RXOCF-x
x = 0 - 511
Interface Switch
AOIS
RXOIS
RXOIS-x
x = 0 - 511
Timing Function
AOTF
RXOTF
RXOTF-x
x = 0 - 511
AOCON
RXOCON
RXOCON-x
x = 0 - 511
AODP
RXODP
RXODP-x-y
x = 0 - 511 y=0-3
SOTRXC
RXOTRX
RXOTRX-x-y
x = 0 - 511 y = 0 - 15
TE LE C
TG
MO Class
O
Hardware Function
M
NOTE: This table can be used as a reference when conducting the MO Definition exercise on completion of this chapter.
Concentration Digital Path
Transceiver Controller
TX
Transmitter
AOTX
RXOTX
RXOTX-x-y
x = 0 - 511 y = 0 - 15
RX
Receiver
AORX
RXORX
RXORX-x-y
x = 0 - 511 y = 0 - 15
TS
Timeslot
AOTS
RXOTS
RXOTS-x-y-z
x = 0 - 511 y = 0 - 15 z=0-7
IO
Figure 7-7: G12 Managed Object Table
ET H
To address a G12 MO from the BSC, you must enter “RXO” before the MO name. For example, “RXOTG” addresses the TG or “RXOCF” addresses the CF in the RBS 2000.
LZT1380709 R2A
After the MO is addressed by name, an instance number must be specified; for example, “RXOTG-100” addresses TG 100. The CF, CON, IS, and TF are addressed by the same instance number as their TG, e.g., RXOCF-100, RXOIS100, etc. The DPs are addressed using the same instance number as their TG, and a local index within the TG, since it is possible to use up to four PCM lines to an RBS 2000. PCM-A corresponds to RXODP-[TG #]-0, PCM-B to RXODP-[TG #]-1, and so forth.
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GSM BSS Integration for Field Maintenance
17
The TRXCs, RXs, and TXs are addressed using the same instance number as their TG and a local index within the TG. The TRXC and its dedicated RX and TX functions are related by using the identical local indices, e.g., RXOTX-100-0.
20
The TSs are addressed by the same instance number as the TG, a local index for the TRXC (within that TG), and a local index within the TRXC, e.g., RXOTS100-0-1 to address timeslot 1 connected to TRXC 0 in TG 100.
When defining MOs in the BSC, the recommended order is TG, CF, IS, TF, CON (if necessary), DPs, TRXCs, TXs, RXs, and finally TSs.
RXOTG-99
O
RBS
M
Figure 7-8 gives a more graphical display of RBS 2000 MOs and how they are addressed in the BSC.
DXU (hardware)
TE LE C
RXODP-99-1
RXOIS-99
A-bis
RXODP-99-0 RXOCON-99
RXOTF-99 RXOCF-99
TRU-1 (hardware)
TRU-2 (hardware)
RXOTRX-99-0
RXOTRX-99-1
RXOTX-99-0
RXOTX-99-1
RXORX-99-0
RXORX-99-1
RXOTS-99-0-0 RXOTS-99-0-1 RXOTS-99-0-2 RXOTS-99-0-3 RXOTS-99-0-4 RXOTS-99-0-5 RXOTS-99-0-6 RXOTS-99-0-7
RXOTS-99-1-0 RXOTS-99-1-1 RXOTS-99-1-2 RXOTS-99-1-3 RXOTS-99-1-4 RXOTS-99-1-5 RXOTS-99-1-6 RXOTS-99-1-7
IO
Figure 7-8: MOs – Software and Hardware
ET H
It is important to note the differences between a TRU and a TRX. TRU (RBS hardware) numbering begins with “1”. TRX (RBS MO) numbering begins with “0”.
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LZT1380709 R2A
TRU11 = TRX10
HC
TRU12 = TRX11
TRU9 = TRX8
HC
TRU10 = TRX9
TRU7 = TRX6
HC
HC
TRU5 = TRX4
20
CDU
M
TRU6 = TRX5
TRU3 = TRX2
HC TRU4 = TRX3
TRU1 = TRX0
D X U
HC
CDU
CDU
TRU8 = TRX7
TRU 6 = TRX-5
TRU 5 = TRX-4
TRU 4 = TRX-3
CDU
CDU
TRU2 = TRX1
CDU
TRU 3 = TRX-2
RBS 2106/2206 TRU 2 = TRX-1
D X U
TRU 1 = TRX-0
RBS 2102/2202
17
Managed Objects
O
RXD tells the TRU to use RXA, RXB or both.
MPWR is the MAXIMUM power that the TX can use (in dBm).
TE LE C
BAND is the frequency band that the TX and RX operate in.
Figure 7-9: TRU/TRX Relationship The command to define MOs is rxmoi.
RXOTG-99
DXU (hardware)
1ST: RXOTG
2ND: RXOCF
3RD: RXOIS
RXOTF
RXOCON
ET H
IO
RXODPs
LZT1380709 R2A
4TH: RXOTRXs 5TH: RXOTXs RXORXs 6TH: RXOTSs
RXODP-99-0 RXODP-99-1 RXOCON-99
RXOIS-99
MOs should be defined according to their hierarchy:
RXOTF-99 RXOCF-99
TRU 1 (hardware)
TRU 2 (hardware)
RXOTRX-99-0
RXOTRX-99-1
RXOTX-99-0
RXOTX-99-1
RXORX-99-0
RXORX-99-1
RXOTS-99-0-0 RXOTS-99-0-1 RXOTS-99-0-2 RXOTS-99-0-3 RXOTS-99-0-4 RXOTS-99-0-5 RXOTS-99-0-6 RXOTS-99-0-7
RXOTS-99-1-0 RXOTS-99-1-1 RXOTS-99-1-2 RXOTS-99-1-3 RXOTS-99-1-4 RXOTS-99-1-5 RXOTS-99-1-6 RXOTS-99-1-7
Figure 7-10: MO Definition Hierarchy
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4.2
17
GSM BSS Integration for Field Maintenance
MO States
20
MOs can be in different states depending on what is currently going on in the RBS and, furthermore, what the BSC is doing towards the MOs at the moment (Figure 7-11). Block RXBLI
In to Service RXESI
Define RXMOI
DEF
Automatic
Deblock RXBLE
COM
PREOP
O
UNDEF RXMOE Delete
Automatic
M
NOOP
RXESE Out of Service
TE LE C
Automatic
DEF - MO is defined COM - MO is out Pre-Post Service State PREOP - MO is being brought into operation OPER - MO is operational NOOP - MO is temporarily not operational FAIL - MO is blocked because of faults
Automatic
OPER
Block RXBLI
FAIL
Block RXBLI
Figure 7-11: State Diagram for Managed Objects
After the MOs are defined, the TRXs and the TXs should be dedicated to their cells using the rxmoc command, as shown in the following example: CELL X
CELL Y
CELL Z
rxmoc: mo=rxotrx-1-0, cell=x; rxmoc: mo=rxotrx-1-1, cell=x;
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CDU
CDU
CDU
TRX 0
TRX 4
TRX 8
HC
HC
HC
TRX 5
TRX 9
rxmoc: mo=rxotrx-1-8, cell=z; rxmoc: mo=rxotrx-1-9, cell=z;
TRX 1
ET H
IO
rxmoc: mo=rxotrx-1-4, cell=y; rxmoc: mo=rxotrx-1-5, cell=y;
rxmoc: mo=rxotx-1-0, cell=x; rxmoc: mo=rxotx-1-1, cell=x; rxmoc: mo=rxotx-1-4, cell=y; rxmoc: mo=rxotx-1-5, cell=y; rxmoc: mo=rxotx-1-8, cell=z; rxmoc: mo=rxotx-1-9, cell=z;
Figure 7-12: TRX and TX Cell Dedication
© Ericsson AB 2012
LZT1380709 R2A
Managed Objects
20
17
When defining MOs, the first thing to do is to initiate the MO with its specific data. This is done using the RXMOI command (as seen on the left of Figure 712). This command is one of many that are used to administer the RBS. “RX” stands for Radio Transceiver Administration, “MO” stands for Managed Object, and “I” for Initiate.
M
For a change of, or corrective actions concerning, the MO data, the RXMOC command is used. “C” stands for Change. The MO is now defined. That means that the MO has all the data it needs to be able to function. However, this only concerns the memory of the BSC. Now, the MO must be brought into service. This involves loading all data into the RBS, using the RXESI command. “ES” stands for Managed Object in Service. Using this command, all data is sent to the MO in the RBS.
4.3
TE LE C
O
The next step is to de-block the MO to make it operational. The command to deblock an MO is RXBLE, where “BL” stands for Manual Blocking of Managed Object, and “E” stands for End.
Frequency Hopping
Frequency hopping, which is implemented during MO definition, can reduce the effect of multipath fading. Multipath fading is frequency and location-dependent. With frequency hopping, a non-moving mobile will typically not remain in a specific fading dip longer than one TDMA frame. The low signal-strength dips in multipath fading are thus leveled out, and the mobile will perceive a more even radio environment. This is called frequency diversity.
4.3.1
Synthesizer Hopping
ET H
IO
Synthesizer Hopping means that one transmitter handles all bursts that belong to a specific connection. The bursts are sent "straight on forward" and not routed by the bus.
LZT1380709 R2A
In contrast to Baseband Hopping (on the following page), the transmitter tunes to the correct frequency at the transmission of each burst. The advantage of this mode is that the number of frequencies that can be used for hopping is not dependent on the number of transmitters. It is possible to hop over a lot of frequencies even if only a few transceivers are installed. The gain from frequency hopping can thereby be increased. Synthesizer hopping is often used in a fractional load network, which is characterized by tight frequency reuse and high interference. Each TRX is configured to hop over a large number of frequencies in order to obtain the maximum frequency hopping gain and interference averaging.
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GSM BSS Integration for Field Maintenance
M
20
Synthesizer Advantages: › Can have more frequencies than transmitters (therefore, more effective)
17
A disadvantage with synthesizer hopping is that wide-band hybrid combiners have to be used. This type of combiner has approximately 3 dB loss, making more than two combiners in cascade impractical.
TE LE C
O
Synthesizer Disadvantages: › Cannot be performed on filter combiners › Carrier 0 cannot hop
FHOP this parameter must be set for either SY (SYNTHESIZER)
Figure 7-13: Synthesizer Frequency Hopping
4.3.2
Baseband Hopping
In Baseband Hopping, each transmitter is assigned to a fixed frequency. At transmission, all bursts, irrespective of which connection, are routed to the appropriate transmitter of the proper frequency.
ET H
IO
The advantage with this mode is that narrow-band tunable filter combiners can be used. These combiners have up to 12 inputs for RBS 2000. This makes it possible to use many transceivers with one combiner.
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LZT1380709 R2A
Managed Objects
20
17
Baseband Advantages: › Can be done on any type of filter, not just lossy hybrids. › Carrier 0 can hop
M
Baseband Disadvantages: › Number of frequencies is limited to number of radios (e.g., four radios, max. of four frequencies). Fewer frequencies are less effective
O
FHOP this parameter must be set for either BB (BASEBAND ) Figure 7-14: Baseband Frequency Hopping
TE LE C
FHOP If frequency hopping is used, this parameter must be set for either BASEBAND or SYNTHESIZER. Acceptable values: BB or SY
COMB If using CDU-C, CDU-C+, CDU-G, or CDU-J this must be set to HYBRID. If using CDU-D, it must be set to FILTER. Acceptable values: FLT or HYB TRU 0
TRU 1
TRU 2
TRU 3
IO
DXU
TX RXA RXB TX RXA RXB TX RXA RXB TX RXA RXB
TX-0 TX-1 TX-2 TX-3
CDU-C+
HYBRID COMB
TX TRU0 RXA
CDU-C+
HYBRID COMB
TX-0 TX-1 TX-2 TX-3
TX TRU1
DUPL ALNA
TX TRU2 RXB
TX TRU3
DUPL ALNA
TX-0 TX-1 TX-2 TX-3
Figure 7-15: Frequency Hopping and Combiner Parameters
ET H
4.3.3
LZT1380709 R2A
Terminal Endpoint Identifiers (TEIS) Terminal Endpoint Identifiers (TEIs) are LAPD elements used for Layer 2 addressing to a TRXC or CF in an RBS. TEI values range from 0 to 63 in RBS 2000.
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GSM BSS Integration for Field Maintenance
DXU
› When the RBS is installed, the technician must set the TEIs for the CF.
CF
20
IDB
TEI = 62
OMT
O
› For this reason, a common practice is used for consistency.
M
› The TRXs’ TEI is fixed according to the TRX position in the RBS cabinet. › These TEIs must match those used in the BSC when the CF and TRXs are defined.
17
RBS
TE LE C
Figure 7-16: Terminal Endpoint Identifiers (TEIs)
When defining the CF’s TEI (at the BSC), the default value is 62. However, it is possible to use a different value for CF TEI addressing other than the default. In some cases, it is necessary to use different TEI values, for instance, when configuring a multi-drop connection in an RBS 2000, the TEI for the CF must be different for the different connected TGs. The corresponding TEI for the CF value must also be recorded in the IDB at the time of installation using the OMT connected to RBS 2000 (or by remote OMT).
ET H
IO
When defining the TEI values for TRXCs, it is recommended that the same TEI value as the corresponding value of the TRXC be used. For instance, if the TRXC is defined as “RXOTRX-99-1”, the TEI value should be “1”. The TEI values for multiple TRXCs must be unique within a single TG, and these values must also be recorded in the IDB via OMT at the time of installation.
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LZT1380709 R2A
Managed Objects
BSC
A-bis
RXOCF-98 TEI=62
17
3x2 site or 2-2-2 site RXOTG-98
RXOTRX-98-0 TEI=0
20
RXOTRX-98-1 TEI=1
RXOTRX-98-2
TEI is a parameter for each RXOCF and RXOTRX. It identifies them on that A-bis interface.
TEI=2
RXOTRX-98-3
M
TEI=3
RXOTRX-98-4
TE LE C
O
TEI=4
RXOTRX-98-5 TEI=5
Figure 7-17: Typical TEIs for CF and TRXs (1 of 4)
BSC
A-bis
RXOCF-97
ET H
IO
TEI=62
LZT1380709 R2A
3x1 site or 1-1-1 site
RXOTG-97
RXOTRX-97-0 TEI=0 TRX not defined No TEI RXOTRX-97-2 TEI=2 TRX not defined No TEI RXOTRX-97-4 TEI=4 TRX not defined No TEI
Figure 7-18: Typical TEIs for CF and TRXs (2 of 4)
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GSM BSS Integration for Field Maintenance
1x2 site
A-bis
RXOTG-96
RXOCF-96
RXOTRX-96-0
TEI=62
TEI=0
20
RXOTRX-96-1
17
BSC
TEI=1
1x2 site
M
RXOTG-95
RXOTRX-95-0
TEI=61
TEI=0
O
RXOCF-95
RXOTRX-95-1 TEI=1
TE LE C
Figure 7-19: Typical TEIs for CF and TRXs (3 of 4) Two Separate Sites on the Same A-bis Link Site/TG with 12 TRUs (two cabinets)
A-bis
RXOTG-94
RXOCF-94
RXOTRX-94-0 TEI=0
TEI=62
IO
TEI=6
RXOTRX-94-1
RXOTRX-94-7
TEI=1
TEI=7
RXOTRX-94-2
RXOTRX-94-8
TEI=2
TEI=8
TEI=3
ET H
RXOTRX-94-6
no DXU
RXOTRX-94-3
- 194 -
no CF def
RXOTRX-94-4 TEI=4 RXOTRX-94-5 TEI=5
Balanced cable connecting local buses of two cabinets
RXOTRX-94-9 TEI=9 RXOTRX-94-10 TEI=10 RXOTRX-94-11 TEI=11
Figure 7-20: Typical TEIs for CF and TRXs (4 of 4) Extension Cabinet Site
© Ericsson AB 2012
LZT1380709 R2A
Managed Objects
Digital Connection Points (DCPs)
17
4.4
20
The connection of the control and speech/data channels from the RBLT devices through the IS in the DXU to the TRXs is automatically established when the TRXs are put into service (command RXESI). The connections for the units are called Digital Connection Points (DCPs) and these represent a 64 kbps connection.
M
When defining the CON and TRXCs in an RBS, it is necessary to establish their DCPs in the BSC. DCPs are specific to the IS and are the input points for the CON and A-bis RBLT devices, and the output points for both speech and signaling paths to the individual TRXCs.
O
The CON must have 24 DCPs defined on the input to the IS. The value range for CON DCPs is 0 through 511, but typically these are always values 64 through 87. For example:
TE LE C
DCP=64&&87 would be the DCP-related parameter for RXOCON.
A TRXC has two parameters defined for DCPs. DCP1 is one IS output for signaling to the TRXC itself, and DCP2 is two outputs for speech to the TRXC’s timeslots (TSs). Example 1: DCP1=128 and DCP2=129&130 for non-EDGE TRUs Example 2: DCP1=178 and DCP2=179&&186 for EDGE TRUs RXOCF
IO
RXOIS
ET H
A-bis
in DCPs out 128 -
129
-
130
TRU
RXOTRX-99-0
DCP1
RXOTX-99-0
signaling
RXORX-99-0
speech RXOTS-99-0-0 speech
RXOTS-99-0-1 RXOTS-99-0-2 RXOTS-99-0-3
DCP2 DCP1 is a DCP output of the RXOIS that connects the signaling DS0 to the RXOTRX DCP2 is the two DCP outputs of the RXOIS that connect the 8 speech sub-channels on 2 DS0s or 8 DS0s for EDGE equipment
RXOTS-99-0-4 RXOTS-99-0-5 RXOTS-99-0-6 RXOTS-99-0-7
Figure 7-21: Digital Connection Points (DCPs)
LZT1380709 R2A
© Ericsson AB 2012
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GSM BSS Integration for Field Maintenance
17
The A-bis interface will have DCPs assigned for each of its RBLT devices, but this will be further discussed in Chapter 8.
128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145
DS0 used for signaling link (DCP1)
RXOTRX-98-0 RXOTRX-98-1 RXOTRX-98-2
M
RXOTRX-98-3 RXOTRX-98-4 RXOTRX-98-5
FPN: DCP1 for TRX 6 will be 160!
O 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177
RXOTRX-98-6 RXOTRX-98-7
TE LE C
. . . . .
DCP outputs
Abis
0 1 2 3 . . . 28 29 30 31
DCP inputs
. . .
RXOIS
Two DS0s used for speech/data (DCP2)
0 1 2 3 4 5 6 7 8 9 10
20
The DCPs range depends of the EDGE capability of the TRU. The next figures show the difference between non-EDGE TRUs and EDGE TRUs.
23 / 31
E1
T1
RXOTRX-98-8 RXOTRX-98-9 RXOTRX-98-10 RXOTRX-98-11
Figure 7-22: DCP Allocations IS and non – EDGE TRXs PCM C
PCM D
DP-0
DP-1
DP-2
DP-3 DCP= 64&&87
DCP= 319&&349
DCP= 32&&63
DCP= 0&&31
CON
DCP2= 278&&285
DCP1= 277
DCP1= 268
DCP2= 269&&276
DCP1= 259
DCP2= 260&&267
DCP2= 251&&258
DCP1= 250
DCP1= 241
DCP2= 242&&249
DCP1= 232
DCP2= 233&&240
DCP2= 224&&231
DCP1= 223
DCP1= 214
DCP2= 215&&222
DCP1= 205
DCP2= 206&&213
DCP2= 197&&204
DCP1= 196
DCP2= 188&&195
IS DCP1= 187
DCP2= 179&&186
DCP1= 178
IO
ET H
DCP= 287&&317
PCM B
DXU-21
PCM A
TRX-0
TRX-1
TRX-2
TRX-3
TRX-4
TRX-5
TRX-6
TRX-7
TRX-8
TRX-9
TRX-10
TRX-11
TEI-0
TEI-1
TEI-2
TEI-3
TEI-4
TEI-5
TEI-6
TEI-7
TEI-8
TEI-9
TEI-10
TEI-11
Figure 7-23: DCP Allocations for EDGE RBS
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Cell/Site Integration
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Objectives
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8 Cell/Site Integration
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Finish MO and Cell integration, using the WinFIOL and corresponding commands connected in the BSC: › Define the purpose of an RBLT device › Identify the commands to bring an MO into service and to unblock it › Execute the process of connecting a cell to a site › Use the process of loading software into an RBS › List various RBS maintenance commands
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Figure 8-1: Objectives
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Introduction
20
The purpose of this chapter is to give an overview of the final steps needed to complete the Cell/Site Integration process.
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We have already discussed the definition of a cell (in Chapter 6) and the definition of MOs (in Chapter 7). It is now time to establish the connection between the BSC and the BTS via the A-bis path (or RBLT), bring the site into service, deblock it, connect the cell to the BTS, and activate the cell. The following sections give information on how to accomplish these tasks.
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Additionally, we will also discuss the process of loading software from the BSC to the RBS.
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Cell/Site Integration
RBLT Connections
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To establish the RBLT device connections to the BTS – and specifically to the RXOIS (Interface Switch) – the command RXAPI is used: RXAPI:MO=mo, DEV=dev, DCP=dcp, [,RES64K]; Command parameters:
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DEV – Refers to the devices on the RBLT that are being used towards the TG DCP – Refers to the DCPs in the RXOIS used to terminate the RBLT devices in the RBS RES64K – A 64 kbit/s Abis path will be reserved for use by a suitably configured Time Slot (TS) only.
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Up to 124 A-bis paths may be defined per TG. All A-bis paths within a TG must be connected to devices of the same transmission type. For example:
RXAPI:MO=RXOTG-21, DEV=RBLT24-105&&-107, DCP=10&&12; The command line above is exemplified in the Figure 8-2.
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RXAPI:MO=rxotg-21, DEV=rblt-105&&-107, DCP=9&&11;
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SNT= ETRBLT-3
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DIP=3RBLT DEV=RBLT-96 to RBLT-127 105 106107
DCP refers to the DCPs in the RXOIS used to terminate the devices in the RBS.
TRU
RXOCF
RXOIS DCP
DCP
9
-
10
-
11
DEV refers to the devices on the DIP that are being used for the TG.
RXOTG
-
DCPs 9, 10 and 11 are used because the devices (DEV) 105, 106 and 107 are the 9th, 10th and 12th DS0s on the E1
Figure 8-2: Connection from 3RBLT Devices
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DP-2
DP-3
DCP= 287&&317
DCP= 319&&349
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DP-1
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IS
PCM D *
CON
20
DP-0
DCP= 32&&63
PCM C*
DCP= 64&&87
PCM B
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PCM A
DCP= 0&&31
The DCP connections pre-established on the RXOIS are as follows:
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Important: take care with the PCM Model (E1 or T1) and the DCP ranges.
* DXU-21
only.
Figure 8-3: DCP Allocations on Input of RXOIS
For the DCP used for the TRUs, look the Chapter 7. An example setup for two sites on one A-bis path:
RXAPI: MO=RXOTG-21, DEV=RBLT-33&&-38, DCP=1&&6;
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RXAPI: MO=RXOTG-22, DEV=RBLT-39&&-44, DCP=7&&12;
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RXOTG-21
2nd
34
DCP
3rd
35
4th
36
5th
37
6th
38
7th
39
8th
40
9th
41
0 1 2 3 4 5
Site 1 (TG-21)
rxapi:mo=rxotg-21, dev=rblt-33&&-38, dcp=1&&6;
Site 2 (TG-22)
rxapi:mo=rxotg-22, dev=rblt-39&&-44, dcp=7&&12;
6 7 ...
RXOTG-22
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DCP 6 7 8 9 10 11
11th 43 12th 44 DEV= RBLT
12 13 ...
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45 ...
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10th 42
...
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1st
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Cell/Site Integration
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Figure 8-4: RXOTG DCP Set-up for Two Sites
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Bringing the Cell Site Into Service and Deblocking
20
After reviewing the MO State diagram below Figure 8-5, as well as considering the next step in the Cell/Site Integration process, it is time to bring the cell site into service and deblock it. Block RXBLI
In to Service RXESI
Define RXMOI
DEF
Automatic
Deblock RXBLE
COM
PREOP
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UNDEF RXMOE Delete
Automatic
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NOOP
RXESE Out of Service
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Automatic
DEF - MO is defined COM - MO is out Pre-Post Service State PREOP - MO is being brought into operation OPER - MO is operational NOOP - MO is temporarily not operational FAIL - MO is blocked because of faults
Automatic
OPER
Block RXBLI
FAIL
Block RXBLI
Figure 8-5: State Diagram for Managed Objects
3.1
Bringing Site Into Service
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The command RXESI ((Radio X-ceiver Administration Managed Object In Service, Initiate) is used to bring an RBS site, specifically the MOs that make up the site, into service.
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RXESI: MO=mo, SUBORD;
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Because many MOs make up a site, all MOs, from the TG down to the TSs, must be brought into service in order for the site to function properly. The SUBORD parameter makes it possible to put all the associated MOs for a site into service in one command line. By using SUBORD, all MOs subordinate to the MO specified would be affected. For instance, if you want to put a TG (e.g., TG 100) and all its subordinate MOs into service, you would type the following command line: RXESI: MO-RXOTG-100, SUBORD;
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Cell/Site Integration
Deblocking a Site
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The same circumstances can be applied to deblocking a site as to bringing a site into service. The command RXBLE (Radio X-ceiver Administration Manual Blocking of Managed Object, End) is used to deblock a TG: RXBLE: MO=mo, SUBORD;
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RXBLE: MO=RXOTG-100, SUBORD;
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Yet again, using the SUBORD parameter will allow you to deblock a TG (e.g., TG 100) and all its subordinate MOs:
Bring TG into service Deblock TG -
rxesi:mo=rxotg-x; rxble:mo=rxotg-x;
Bring CF into service Deblock CF -
rxesi:mo=rxocf-x; rxble:mo=rxocf-x;
Bring IS into service Deblock IS -
rxesi:mo=rxois-x; rxble:mo=rxois-x;
Bring TF into service Deblock TF -
rxesi:mo=rxotf-x; rxble:mo=rxotf-x;
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RXOIS
Bring TRXs into service Deblock TRXs -
rxesi:mo=rxotrx-x-0&-2&-4; rxble:mo=rxotrx-x-0&-2&-4;
RXOCF
RXOTF
RXOTRX
RXOCON
RXOTX
RXORX
RXOTS
RXODP
NOTE: The “subord” parameter may be used as follows:
Bring TXs into service Deblock TXs -
rxesi:mo=rxotx-x-0&-2&-4; rxble:mo=rxotx-x-0&-2&-4;
Bring RXs into service Deblock RXs -
rxesi:mo=rxorx-x-0&-2&-4; rxble:mo=rxorx-x-0&-2&-4;
Bring TSs into service Deblock TSs -
rxesi:mo=rxots-x-0-0&&-7&rxots-X-2-0&&-7&rxots-X-4-0&&-7; rxble:mo=rxots-x-0-0&&-7&rxots-X-2-0&&-7&rxots-X-4-0&&-7;
rxesi: mo= rxotg-x, subord; rxble: mo= rxotg-x, subord;
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Figure 8-6: Bringing RBS into Service and Deblocking
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Cell Connection and Activation
4.1
Connect Cell to BTS
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Once a cell is defined, the BSC knows the cell as a set of data. However, the cell does not have a connection to a BTS. No BTS is configured yet according to the parameters, as defined in configuration power data, control channel data, or frequency data. Therefore, the cell must be connected to a BTS (TG) before being activated. This is done using the following command line:
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RXTCI: MO=mo, CELL=cell, CHGR=chgr;
Cell
RXTCI:MO=rxotg-x,CELL=cell,CHGR=0;
BSC
RBS Site
Figure 8-7: Connect Channel Group(s) to RBS
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The connection is carried out via the Channel Group (CHGR). A normal cell (no subcell structure) is always connected via CHGR=0. In the case of subcells, the underlaid subcell is always CHGR=0, whereas the overlaid subcell is CHGR=1.
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4.2
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Activate Cell
When defining cell data, the state of a cell is HALTED (off air). After cell data definition, the state of the cell must be changed to ACTIVE (on air) using the following command line: RLSTC: CELL=cell, CHGR=chgr, STATE=state;
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RLSTC:CELL=cell, STATE=active;
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BSC
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Figure 8-8: Activate Cell
4.3
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Alternatively, an individual CHGR can be activated. During cell activation, the cell data for description and configuration is downloaded to the connected TG. The purpose of the cell state is to control the input of data to the cell to minimize the effect on ongoing traffic. Very important data can only be changed in the HALTED state, for example, cell description data (CGI, BCCHNO, etc.).
Transitioning from HALTED to ACTIVE The defined cell configuration data is used for configuration. Logical channels are created, and the BCCH for the cell is activated. System information messages are distributed to the MSs.
4.4
Verification
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Once you have activated the cell, it is a good idea to check the cell resources and BTS configuration data. The two commands to do this, respectively, are RLCRP and RXCDP.
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Cell Resource Data
The following command line is used to check the resource data of a particular cell: RLCRP: CELL=cell;
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Below is an example of a printout resulting from running this command:
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Figure 8-9: Cell Resource Data
4.6
BTS Configuration Data
The following command line is used to view the configuration data of MOs:
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RXCDP: MO=mo;
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In the case of a newly connected and activated cell, it is recommended that this command be run on the TG to view how it is configured.
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NOTE: You can use ALEX to research the information printed out as a result of running the RLCRP or RXCDP commands.
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Cell/Site Integration
Loading New RBS Software
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The hardware and MOs in the RBS require, on occasion, new software to work. This software is downloaded over the A-bis interface to the RBS. The command to initiate the software-download function is RXPLI (Radio X-ceiver Administration Function Change and Program Load of Managed Objects, Initiate). RXPLI initiates one of the following sub-functions:
The function change of the software for all MOs
The program loading of MO instances, specified by the command parameter
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DXU
A-bis
FLASH Memory
TRU(s)
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TRU Application TRU INIT
1
DXU Application DXU INIT
TRU Application
3
TRU INIT
2
3
FLASH Memory
DRAM PROM
DATA
Fixed Boot
Executable TRU Application
DRAM
PROM
DATA
Fixed Boot
Executable DXU Application
New software is loaded from the BSC to the RBS via the A-bis Interface. Traffic is unaffected. 2 Software is loaded from DXU to TRU. Traffic is unaffected.
1
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3 Traffic is interrupted while new software is loaded from FLASH
into DRAM.
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Figure 8-10: Loading New Software to RBS
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Figure 8-10 shows the RBS software load process. Below is a description of
what is happening in each step: 1) New software is loaded from the BSC to the RBS via the A-bis Interface. Traffic is unaffected, and this part of the process lasts approximately 20 minutes. 2) Software is loaded from the DXU to the TRUs and ECU (if applicable). Traffic is unaffected, and this part of the process lasts approximately two to three minutes.
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3) Traffic is interrupted for approximately 30 to 45 seconds while new software is loaded from FLASH memory into DRAM. The following command line accomplishes Steps 1 and 2:
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RXPLI: MO=RXOTG-x, LOAD [,UC];
This command would be run during regular operating hours. It takes a long time to accomplish these steps for just a few RBSs and should be done only a few at a time.
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The following command line would be used for Step 3:
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RXPLI: MOTY=RXOTG, START;
This command should be done only during the maintenance window, as it will bring down the cells for a short period of time.
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DXU
A-bis
2
Flash Memory
1
DRAM
Executable DXU Application
1
IO
2
3
3
TRU(s) TRU FLASH
DRAM Executable TRU Application
3
New software is loaded from the BSC to the RBS via the A-bis Interface. Traffic is unaffected. (~20 min) Software is loaded from DXU to TRU and ECU. Traffic is unaffected. (~2-3 min) Traffic is interrupted for 30-45 seconds while new software is loaded from FLASH into DRAM.
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Figure 8-11: RXPLI Command
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Function change and program load of MOs use the software version defined for a CF, TRXC, or TG. MO types CF, TRXC, or TG in service have two software versions defined: actual software version and replacement software version.
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Cell/Site Integration
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A command ordering software loading of a CF, TRXC, or TG always uses the replacement software version, and after processing the command, the identity of its actual software version is changed into replacement software version. To set the replacement software version, use the RXMSC command (Radio X-receiver Administration MO In-service Data, Change). If a CF or a TRXC does not have a specific software version assigned, the software version assigned to its TG is used. If the command is given with the parameter MOTY, this initiates the function change of software to all manually deblocked MOs within a BTS logical model (Step 3).
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Function change is performed for a number of TGs and its subordinate MOs in parallel. MOs that do not share the same physical path are loaded in parallel. This allows for the traffic in the rest of the system to remain unaffected (Steps 1 and 2).
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During the function change, there is no software loading for manually blocked MOs. If a CF, TRXC or TG is manually blocked, then its actual software version will be changed to replacement software version and then is loaded when it is manually de-blocked. Only one function change command is allowed at any one time in the BSC. If the command is given with the parameter MO, this will load the specified MOs. Program loading is allowed for MOs in service. The program loading process for a CF, TRXC, or TG is identical to its function change process. This program load command can handle up to 32 MO instances. This function has the capability of handling up to 16 commands simultaneously. › rxmsp - Find the operational status for all Managed Objects (MOs) in your jurisdiction (requires a script) › rxmfp - Find any faulty MOs in your jurisdiction (can be done with single command)
IO
› rlcrp - Show the radio resources (active traffic channels) of all cells (single command)
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› rxelp - Outputs the fault logs for all MOs › rxapp - Show the status of A-bis paths to all Transceiver Groups (TGs) in your jurisdiction › rxlti - Initiates a loop test that is used to verify that the correct connection exists between the TRC and a time slot within the RBS › allip - Prints an alarm list › rxtei - Initiates a test of one or more MOs in the RBS › dtstp - Initiates a printout of the state for the specified DIP
Figure 8-12: Useful Maintenance Commands
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Intentionally Blank
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